Libya's rebel stronghold of Benghazi came under attack on Saturday morning, with at least two air strikes and sustained shelling of the city's south sending thick smoke into the sky.
Multiple explosions could be heard from the centre of the city, as a military plane flew low overheard, and the Southern skyline was dominated by plumes of black smoke.
Retaliatory mortar fire sounded, and on the roads pick-up trucks mounted with machine guns could be seen, after a night in which explosions and gunfire sounded continuously.
The first air strike came at 7.20 GMT (0520 GMT) and the second followed around 20 minutes later, but the identity of the planes carrying out the strikes could not be immediately identified.
At 8.17 am local time, a series of several small explosions, possibly from Katyusha rockets, produced at least seven smaller columns of black smoke south of the city.
At 8.40 am local time, a military plane could be heard flying low over the centre of the city, and several loud explosions were heard shortly afterwards.
The air strikes came after the Libyan Government said it was observing a ceasefire that it announced shortly after the United Nations voted to authorise use of force against Muammar Gaddafi's troops.
But the rebel forces who have been trying to overthrow the Libyan leader said his troops had continued to bombard cities, violating the ceasefire continuously since its declaration.
On Friday evening, residents of Benghazi had braced for an imminent attack, after reports Gaddafi's troops were just 50 kilometres (30 miles) south of the city and planning an evening assault.
In Tripoli, Libya's deputy foreign minister had denied there were any plans to attack the rebel bastion and said the government forces would not breach the ceasefire.
"The armed forces are now located outside the city of Benghazi and we have no intention of entering Benghazi," Khaled Kaaim told reporters.
Kaaim also called for the immediate deployment of foreign observers, saying otherwise "the accusations and counter-accusations will not stop."
On Friday, the United States accused Gaddafi of violating the truce, and President Barack Obama delivered a blunt ultimatum to the Libyan leader, threatening military action if he ignores non-negotiable UN demands for a ceasefire and a retreat from rebel bastions.
France is due to host later Saturday what it said would be a "decisive" summit with the European Union, Arab League and African Union, as well as UN chief Ban Ki-moon, on taking UN-sanctioned military action in Libya.
France's ambassador to the United Nations, Gerard Araud, said he expected military intervention within hours of the summit.