The town is Gaddafi's biggest remaining Libya stronghold and rebel commanders know his forces are dug in for a bloody battle.
For now opposition forces have held their positions to the east and west as they wait for tribal elders to negotiate with Gaddafi fighters.
But Shamsiddin Ben-Ali, a spokesman in the rebel city of Benghazi, said 800 people had been killed in the past three days.
"Many of the people of Sirte are on our side now and want to be part of the revolution," he said. "The people with guns though are still resisting."
The death toll raises a bloody conundrum for the country's new leaders: rushing in could spell a military disaster but waiting is costing a very high price in civilian casualties...
-- bth: that is an awful lot of people in 3 days for a war the western media has declared over.