A spokesman for ousted Libyan leader Muammar Gaddafi has claimed that NATO air strikes have killed 151 people in Sirte over the past two days.

Gaddafi spokesman Moussa Ibrahim, in a satellite phone call to Reuters in Tunis, also said the city's main hospital had run out of medical supplies and power.

His claims could not immediately be verified as Sirte, Gaddafi's hometown, is largely cut off from communication and is besieged on three fronts by ruling National Transitional Council forces.

A NATO official told Reuters that it had attacked Sirte over the last 48 hours, but that the most significant target was a Gaddafi command centre.

"The compound was clearly a military target since (Gaddafi) forces were using it to coordinate and support operations against civilians," the official said.

At the time of that strike, NATO had no indication there were any civilians in the area and Ibrahim's claims of civilian deaths were "unsubstantiated," he said.

"Between yesterday and this morning, 151 civilians were killed inside their homes as the Grad rockets and other explosives fell upon their heads," Mr Ibrahim said.

"The city hospital stopped functioning altogether last night. Patients died simply because nothing can be done to help them."