Anti-Gaddafi forces took heavy losses as they pushed on Wednesday toward the ousted despot's compound in his birthplace Sirte, while also being beaten back in his other remaining bastion, Bani Walid.

On the political front, a member of Libya's new ruling National Transitional Council (NTC) said formation of a transitional government, already delayed by disputes over power-sharing, had been postponed until they had won control of the entire country.

In a radio message, Muammar Gaddafi hailed the resistance put up in Bani Walid, where the NTC said four of their fighters were killed and 11 wounded in fierce clashes on Tuesday with forces loyal to the toppled leader.

The losses were heavier in Sirte, where NTC fighters are battling their way to the heart of the sprawling Mediterranean city, site of a Gaddafi compound and bunkers.

Fighting which raged into the night on Tuesday centered around the Mahari hotel in eastern Sirte where NTC combatants engaged loyalist troops in close quarter skirmishes, a commander said.

"More than 10 of our fighters have been killed today in face-to-face fighting near Mahari hotel," said the commander, who asked not to be named as the information was sensitive.

The NTC fighters and Gaddafi's diehards clashed "in street fights and shot at each other from close range with Kalashnikovs and rocket-propelled grenades", the commander said.

The NTC fighters had early on Tuesday captured Sirte's port, marking a key victory in the battle for control of Gaddafi's hometown.

But they expected a ferocious fight for control of the compound, the nerve center of the remaining resistance where some of Gaddafi's family are thought to be holed up.

NTC fighter Fateh Marimri, who drove out of Sirte's eastern gate in what he said was a captured Gaddafi off-road vehicle, reported heavy fighting around the Mahari hotel.

"They are using heavy weapons but we are not, as we want to cause minimum damage to civilians," Marimri said.

"They are now fighting us in civilian clothes and there are African mercenaries everywhere in Sirte."

He also said Gaddafi's family members were inside Sirte, backed by a "large number of his forces", but did not give names.