Cairo: The whereabouts of Libyan strongman Muammar Gaddafi, who has ruled the oil rich nation uninterrupted for 42 years, remained a mystery as rebel forces swept into the capital Tripoli to jubilant crowds.

Al-arabiya quoting its correspondent in the Libyan capital said that Gaddafi was in the Tajura-Cardiac hospital. But said there were no reports on whether Gaddafi was undergoing treatment in the hospital or simply taking refuge.

But diplomatic sources quoted by an agency reported that the Libyan strongman was in Tripoli in his Bab al-Aziziya command and control centre.

The Bab al-Aziziya compound has been regularly pounded by NATO airstrikes and most of the buildings in the compound have been flattened.

Rebel sources said that Gaddafi had constructed a number of deep bunkers in the complex where he could take cover.

Al-arabiya quoting Ibrahim Saad, secretary general of the National Front for the Salvation of Libya, that the whereabouts of Gaddafi were known to rebels and that an announcement about the matter would likely be made within hours.

The opposition forces have captured two of the Libyan dictator's sons. Saif al-Islam, who along with his father faces charges of crimes against humanity at the International Criminal Court in the Netherlands. Another son, Mohammad, was under house arrest.

Mohammad Gaddafi was captured in dramatic circumstances while giving an interview to a channel.