Soldiers traded rocket fire with Gaddafi loyalists as they edged from the eastern suburbs into the city.
Two days ago government forces had attacked from the west of the Mediterranean city but retreated after a short time.
The BBC reports that hundreds of civilians are leaving the city to escape the fighting. Many are unaware that Tripoli has fallen to the National Transitional Council.
Sirte is a sprawling city and much of the fighting has been conducted over a long distance, with artillery and tank shells and Nato air strikes.
Sirte and Bani Walid, about 250km further west, are the only two major cities still holding out against the NTC.
Fighting is continuing around Bani Walid, with rebel pounding the heavily defended city with heavy artillery and mortars.
So the rebel road trip is nearly over. They started off by getting their arses kicked by Gaddafi’s forces until NATO stepped in and fried anything that moved on Gaddafi’s side. Now they are just two towns away from conquering the whole country and hanging out the ‘Under New Management’ banner to the world.