(adds detail, background)
LONDON, Feb 21 (Reuters) - Military aircraft attacked crowds of anti-government protesters in the Libyan capital Tripoli on Monday, Al Jazeera television said.
A Libyan man, Soula al-Balaazi, who said he was an opposition activist, told the network by telephone that Libyan air force warplanes had bombed "some locations in Tripoli".
He said he was talking from a suburb of Tripoli.
No independent verification of the report was immediately available.
An analyst for London-based consultancy Control Risks said the use of military aircraft on his own people indicated the end was approaching for Muammar Gaddafi.
"These really seem to be last, desperate acts. If you're bombing your own capital, it's really hard to see how you can survive, " said Julien Barnes-Dacey, Control Risks' Middle East analyst.
"But I think Gaddafi is going to put up a fight. I think the rumours of him fleeing to Venezuela are going to prove wide of the mark. In Libya more than any other country in the region, there is the prospect of serious violence and outright conflict."
British Foreign Secretary William Hague said earlier that Gaddafi might be heading for Venezuela, but a senior government source in Caracas denied that. (Reporting by Giles Elgood; Editing by Angus MacSwan)