Libya conflict: Confusion over Mutassim Gaddafi's fate
There are conflicting reports in Libya about the fate of one of ousted leader Col Muammar Gaddafi's sons.
Some figures from the National Transitional Council told news agencies Mutassim Gaddafi had been seized in the family's embattled hometown of Sirte.
However, a military commander in the city denied the claims, which have sparked celebratory gunfire in several cities.
NTC forces say they now control most of Sirte, following fierce fighting.
Where is Gaddafi?
There have been false reports of the capture of senior Gaddafi figures in the past, including another son, Saif al-Islam, and Gaddafi spokesman Moussa Ibrahim.
But if confirmed, Mutassim Gaddafi's capture would be a major breakthrough for the NTC, says the BBC's Caroline Hawley in Tripoli.
He is a senior officer in Col Gaddafi's army and was a national security adviser to his father.
The NTC would want to question him as to the whereabouts of his father and other family members such as Saif and another son Khamis - both in Col Gaddafi's inner circle - analysts say.
Col Gaddafi is believed to be somewhere in Libya's southern deserts. His supporters are also holding out in the town of Bani Walid.
Reuters news agency quotes NTC officials as saying Mutassim was captured as he tried to escape Sirte in a car with a family, after shaving off his long hair to disguise his appearance.
The officials said he had been taken to Benghazi, was being questioned in a military camp and was uninjured but exhausted.
NTC adviser Abdelkarim Bizama told AFP news agency on Wednesday that Mutassim "was captured at Sirte and was transferred to Benghazi".
"We did not announce the capture earlier to avoid that [his family or aides] try to free him," he added.
However, a brigade commander in the city, Wesam Bin Hamid, told the agency claims he had been captured were false.
Mutassim Gaddafi's presence in the city, and that of several other senior figures in the former regime, is believed to be responsible for the fierce resistance the anti-Gaddafi fighters have encountered.
On Wednesday the head of Libya's National Transitional Council (NTC), Mustafa Abdul Jalil, said he was optimistic they would soon declare total victory.
"I hope that liberation will be declared in less than a week, after we free Sirte," he said at a news conference with Tunisian Prime Minister Caid Essebsi in Benghazi.
"And within less than a month we will form a transitional government and the youth and women will have a role in that."
The NTC said taking Sirte would be a major step in being able to govern the whole of Libya, giving them full control of the country's ports and harbours.
Thousands of civilians have fled the city in recent weeks but an unknown number are thought to have stayed behind, facing shortages of food, medicine and drinking water.
Cars leaving Sirte are being stopped and searched at checkpoints to prevent escaping pro-Gaddafi fighters passing themselves off as civilians.