Aleppo ceasefire 'stalled' amid heavy clashes
*Ceasefire 'stalled' as clashes resume *15,000 people waiting to evacuate - reports *Russia says it has reached agreement with Turkey on evacuation *'Surrender deal' to allow civilians and opposition fighters to be evacuated from eastern Aleppo *People are burning possessions fearing looting by the Syrian army *'More than 100 unaccompanied children trapped in a building under fire' - report *Situation a "complete meltdown of humanity" - UN official
A ceasefire in Syria has collapsed just hours after a truce was called.
Heavy clashes including shelling and gunfire raged in the Syrian city of Aleppo on Wednesday after a truce deal meant to halt fighting between government forces and rebels stalled, the Syrian Observatory for Human Rights said.
"The clashes are violent and bombardment is very heavy ... it seems as though everything (the ceasefire) is finished," Rami Abdulrahman, director of the British-based monitoring group, said.
Officials with two Syrian rebel groups and a United Nations official said that Iran had introduced new conditions to the ceasefire and evacuation deal negotiated by Russia and Turkey.
One of the rebel officials and the U.N. official said Iran, which backs some powerful militias fighting in Aleppo on the government side, wanted a simultaneous evacuation of wounded from the villages of Foua and Kefraya that are besieged by rebels.
Earlier, Moscow and Ankara had reached an "understanding" on Tuesday on organizing the evacuation of people from rebel-held areas of the Syrian city of Aleppo, Sergei Ryabkov, Russian deputy foreign minister, was quoted as saying on Wednesday by Interfax news agency.
Meanwhile, witnesses reported a short bout of shelling, hours after a ceasefire was declared.
Syrian Observatory for Human Rights director Rami Abdulrahman said: "The sound of an explosion was heard in areas controlled by (rebel) factions ... it is believed to have been caused by a artillery shell fired by regime forces on the area."
A civilian witness said the attack lasted about half an hour then stopped.
Meanwhile, Russia has also said talks with the US on Syria are a "fruitless talking shop".
A planned evacuation as part of the Aleppo ceasefire has been delayed and may not take place until tomorrow, according to reports.
The evacuation of rebel-held eastern Aleppo may be delayed until Thursday, the pro-Syrian opposition Orient TV reported, citing its correspondent.
The evacuation was expected to have started by dawn on Wednesday. On Tuesday, sources had given different expected start times for the evacuation.
Opposition officials said they had expected a first group of wounded people to leave on Tuesday evening. A military official in the alliance supporting Syrian President Bashir al-Assad had said the evacuation was due to start at 5 a.m. (0300 GMT).
However, none had left by dawn, said a Reuters witness waiting at the agreed point of departure. Twenty buses were waiting there with their engines running but showed no sign of moving into Aleppo's rebel-held eastern districts.
Russia's defence ministry has now claimed 6,000 civilians have left rebel held areas over the past 24 hours.
The UN has said it is not involved in evacuation plans but stands ready to facilitate evacuation.
People have been packing their bags and burning personal possessions as they prepare to evacuate the area, a witness said, fearing looting by the Syrian army and its Iran-backed allied militias when they restore control.
Eastern Aleppo residents were seen burning things they could not take with them, such as pictures, books, clothes and even a car, a Reuters witness said, since an evacuation deal was announced late on Tuesday.
The ceasefire and evacuation agreement brokered by Russia, Syrian President Bashir al-Assad's most powerful ally, and Turkey ended years of fighting in the city and has given Assad his biggest victory yet after more than five years of war.
A ceasefire "surrender deal" allowing civilians and opposition fighters to be evacuated from eastern Aleppo has begun as Russia declared all military action had stopped and the Syrian government assumed control of the former rebel enclave.
The dramatic developments, which appeared to restore the remainder of what was once Syria's largest city to President Bashar Assad's forces after months of heavy fighting and a crippling siege, followed reports of mass killings by government forces closing in on the final few streets still held by the rebels.
Damascus confirmed the evacuation deal and the United Nations envoy for Syria Staffan de Mistura, who was at the Security Council where an emergency meeting for Aleppo was under way, called for immediate access to confirm the end of military operations and oversee the safe departure of tens of thousands of civilians and opposition fighters.
Russia's UN ambassador Vitaly Churkin took to the floor near the end of the session to announce fighting had ended.
"According to the latest information that we received ... military actions in eastern Aleppo are over," he said. "The Syrian government has re-established control over eastern Aleppo."
Minutes earlier, he said "all militants" and members of their families, as well as those wounded in the fighting, were being evacuated through "agreed corridors in directions that they have chosen voluntarily", including the rebel stronghold of Idlib province.
As word spread of the deal, celebrations broke out in the government-controlled western sector of Aleppo, with convoys of cars driving around honking their cars and waving Syrian flags from the windows.
Retaking Aleppo, which has been split between rebel and government control since 2012, would be Assad's biggest victory yet in the civil war.
Aleppo, the country's former commercial powerhouse, has long been regarded as a major gateway between Turkey and Syria and the biggest prize in the conflict.
The agreement came after world leaders and aid agencies issued dramatic appeals on behalf of trapped residents and the UN human rights office said pro-government forces reportedly killed 82 civilians as they closed in on the last remaining rebel areas.
That and other reports of mass killings, which could not be independently confirmed, reinforced fears of atrocities in the final hours of the battle for the city.
UN secretary general Ban Ki-moon told the emergency meeting he had received "credible reports" of civilians killed by intense bombing and summary executions by pro-government forces.
"To the Assad regime, Russia and Iran - three member states behind the conquest of and carnage in Aleppo - you bear responsibility for these atrocities," said US ambassador Samantha Power.
UN humanitarian spokesman Jens Laerke told reporters the situation appeared to be "a complete meltdown of humanity" according to Sky News.
In Turkey, hundreds of protesters gathered outside the Russian consulate in Istanbul, chanting against Russia's involvement in the push to retake rebel-held areas of Aleppo.
Several residents and opposition activists in Syria said government forces carried out summary killings of rebels in neighbourhoods captured on Monday, but the Syrian military denied the claim, saying such allegations were "a desperate attempt" to gain international sympathy.
None of the residents witnessed the alleged killings and the reports came amid deepening chaos in the remaining rebel-held areas. Mohammed Abu Rajab, the administrator of the last remaining clinic in rebel-held parts of the city, said the dead and wounded were being left in the streets.
Bashar al-Ja'afari, Syria's ambassador to the UN, denied any mass executions or revenge attacks, but added it was Syria's "constitutional right" to go after "terrorists", a reference to all opposition fighters.
"Aleppo has been liberated from terrorists and those who toyed with terrorism," he said. "Aleppo has returned to the nation."
Meanwhile the UN children's agency said it had received a report of more than 100 unaccompanied children trapped in a building under fire in eastern Aleppo.
Unicef was concerned over reports of "extrajudicial killings of civilians, including children", said the agency's regional director Geert Cappalaere.
The UN human rights office said it had received reports of pro-government forces killing at least 82 civilians in four neighbourhoods of the rapidly-shrinking rebel enclave, including 11 women and 13 children.
Spokesman Rupert Colville said the reports described pro-government forces entering homes and killing civilians "on the spot".
Rami Abdurrahman of the British-based Syrian Observatory for Human Rights said hundreds of bodies were still under the rubble.
There were conflicting reports about the timing and route of the rebel withdrawal.
Syria's military media said the gunmen would be evacuated through the Ramouseh crossing and from there to rebel-controlled areas of northern Idlib province.
"Aleppo will be declared a secure and liberated city within the coming hours," it said on its Telegram channel.
Osama Abu Zayd, a Turkey-based legal adviser for an umbrella group of rebel factions known as the Free Syrian Army, said the ceasefire went into effect Tuesday evening and that the first groups of rebel fighters would begin evacuating later that day.
Yasser al-Youssef, a rebel spokesman, confirmed the deal, and another spokesman, Ahmed Karali, said those leaving the city would head to rural areas in western Aleppo province, then head north.