Gaddafi Endgame: Fresh gunfire reported in Tripoli
Rebels are in control of 80% of the Libyan capital Tripoli according to reports from the ground, but there are still pockets of loyalist resistance.
Heavy fighting has been reported around Colonel Mummar Gaddafi's al-Aziziya complex and near the Rixos Hotel, where foreign journalists are being housed.
However, scenes of jubilation continued in Tripoli's Green Square today as the 40-year dictatorship appeared to be crumbling.
Opposition fighters captured the dictator's eldest son, Saif al-Islam Gaddafi, and the International Criminal Court said it would contact the rebels to discuss his handover for trial on charges of crimes against humanity.
He was speaking live on Al Jazeera when rebels took his Tripoli home.
Saif was indicted with his father and Libya's intelligence chief earlier this year for allegedly ordering, planning and participating in illegal attacks on civilians in the early days of the violent crackdown on anti-regime protesters.
The court's chief Prosecutor Luis Moreno-Ocampo said he had been detained by "rebel special forces." He declined to give more details of the arrest or the source of the information.
"Tomorrow morning we will talk to them," Moreno-Ocampo said of the rebels. "It is time for justice, not revenge."
Mr Moreno-Ocampo said he did not know where Muammar Gaddafi was.
"We hope that Muammar Gaddafi is also arrested and also faces justice," he said. "There is no more impunity for these crimes."
Mr Moreno-Ocampo charged Gaddafi, his son and his intelligence chief Abdullah al-Sanoussi in May with involvement in a campaign to attack civilians in their homes, shoot at demonstrators with live ammunition, shell funeral processions and deploy snipers to kill people leaving mosques.
Judges at the court issued international arrest warrants for all three men in June, but the court has no police force and was reliant on rebels to detain them.
Mr Moreno-Ocampo said he had evidence of Gaddafi issuing orders and his son organising the recruitment of mercenaries to fight for the regime.
The United Nations Security Council called in February for a probe into atrocities against opponents of Gaddafi's regime.
Last night it was reported that two South African planes had landed at Tripoli airport, leading to rumours that Gaddafi would be given asylum in Africa's most powerful nation.
However, this morning the foreign minister said Gaddafi would not be welcome in South Africa and said no planes had been sent to collect him.
Last night oppositon fighters advanced 20 miles from the west into Tripoli with little resistance, overwhelming a military base and then pouring into the city centre.
Although there were reports that fighting is continuing in some districts, cheering, clapping and celebratory shooting broke out in Green Square, the symbolic heart of the regime, as ecstatic Libyans waved the rebels' tri-colour flag. Others set fire to the green flag of Gaddafi's regime.
Nour Eddin Shatouni, a resident who joined the celebrations, said: "Now we don't call it the Green Square, but we call it Martyrs' Square."
Thousands also celebrated in the rebel stronghold of Benghazi, and Libyans in Britain were said to be celebrating in London's Edgware Road.
Gaddafi's whereabouts where unknown, but Libyan information ministry spokesman Moussa Ibrahim insisted earlier that his loyalists would stand and fight, warning that they had nothing to lose.
In a news conference, he said that the rebels would not have been able to make the advances they had without the support of Nato and he accused the alliance of turning the city into a "hellfire", with 1,300 killed in the fighting.
He issued an apparently vain appeal for a ceasefire and insisted that there had to be a role for Gaddafi in the country or his supporters would be "easy prey for the hateful vengeful side".
However his claims of a bloodbath were dismissed by Guma El-Gamaty, the London representative of the rebel National Transitional Council.
"If it hasn't fallen already, it is falling very fast," he said of the regime to Sky News.
"Gaddafi is nowhere to be known, or found, or seen. There will be no people coming out en masse on Gaddafi's side."
US president Barack Obama said Libya is "slipping from the grasp of a tyrant" as the battle between rebels and longtime leader Muammar Gaddafi reached a "tipping point".
In a statement issued from Martha's Vineyard in Massachusetts, where the president is on holiday, Mr Obama said the surest way for the bloodshed to end is for Gaddafi to relinquish power.
Yesterday, Downing Street said it was clear the "end is near" for the dictator.
"It is clear from the scenes we are witnessing in Tripoli that the end is near for Gaddafi," the No 10 statement said.
"He has committed appalling crimes against the people of Libya and he must go now to avoid any further suffering for his own people."
David Cameron was today chairing a meeting of the National Security Council on Libya (NSC-L) after cutting short his holiday.
The Prime Minister returned to London from Cornwall last night as euphoric Libyan rebels swept into Tripoli.
Libya's ambassador to the United Nations Ibrahim Dabbashi, who switched to the rebel side, said: "This is not the beginning of the end, it is the end."
He told the BBC that Gaddafi could be "replaced" by rebel officials "within a few hours".
Nato Secretary-General Anders Fogh Rasmussen said Gaddafi's regime was "clearly crumbling" and that the time to create a new Libya had arrived.
In a statement, he said: "That transition must come peacefully. It must come now. And it must be led and defined by the Libyan people.
"Nato is ready to work with the Libyan people and with the Transitional National Council, which holds a great responsibility."
Gaddafi last night issued a fresh appeal on state television for Libyans to save the capital.
In a series of audio messages, he called on his supporters to march in the streets of the capital and "purify it" from "the rats". He was not shown in the messages.
The near-collapse of the regime will come has a huge relief to Mr Cameron, who combined with French president Nicolas Sarkozy to launch international airstrikes to protect the rebels last March.
But with the Gaddafi regime stubbornly hanging on, the Prime Minister had increasingly seen the wisdom of his strategy questioned.
The challenge now for the allies will be to help secure as peaceful transition as possible to a democratic government.
Britain has insisted that it will not send peacekeeping troops, but has said that it would assist in other ways.