Saudi-led coalition airstrikes targeting Shiite rebels in Yemen resumed in the southern port city of Aden after a five-day truce came to a close.
They followed talks on the war-torn country's future that were boycotted by the rebels.
Coalition airstrikes hit rebel positions and tanks in several parts of Aden after the ceasefire expired at 11pm local time, Yemeni security officials said.
The ceasefire had not halted all fighting in Yemen between the Shiite rebels, known as Houthis, and government forces loyal to exiled President Abed Rabbo Mansour Hadi.
Earlier yesterday, hundreds of Yemeni politicians and tribal leaders gathered in Saudi Arabia for three days of talks on Yemen's future, but the Houthis refused to participate.
The Shiite rebels reject the main aim of the talks - the restoration of Mr Hadi, who fled the country in March in the face of rebel advances - and the location of the negotiations in Saudi Arabia, which is leading an air campaign against the Houthis and their allies.
The absence of the Houthis means the national dialogue is unlikely to end the violence.
The UN envoy to Yemen, Ismail Ould Cheikh Ahmed, opened the meeting in Riyadh by calling on all parties to ensure that the shaky cease-fire leads to a lasting truce.
"I call on all parties to refrain from any action that disturbs the peace of airports, main areas and the infrastructure of transport," he said.
Since late March, Saudi Arabia has led airstrikes against the Houthis and allied military units loyal to former president Ali Abdullah Saleh.
The campaign is aimed at weakening the Houthis and restoring Mr Hadi, who addressed the talks yesterday.
"This conference taking place today is in support of politics and community, and rejects the coup," he told the gathering.
He urged a return to the political road map through which Mr Saleh stepped down after more than three decades in power following a 2011 Arab Spring-inspired uprising.
His ousting and the road map was backed and overseen by the six-nation Gulf Cooperation Council, which is headquartered in Saudi Arabia, as well as the UN and the US.
Among those taking part in the conference were members of Mr Saleh's former ruling party.
Yemen's conflict has killed more than 1,400 people - many of them civilians - since March 19, according to the UN.
The country of some 25 million people has endured shortages of food, water, medicine and electricity as a result of a Saudi-led blockade.
Humanitarian organisations had been scrambling to distribute aid before the end of the truce.