Two days after the Libyan rebels entered Muammar Gaddafi's Bab Al-Aziziya compound in western Tripoli, hunt for the embattled leader intensified Thursday as rebel fighters were exploring tunnels in the compound.

Right in front of Gaddafi's office building featuring a left- handed fist crushing a U.S. warplane, the rebels found underground tunnels which were about 2 meters high and 2 meters wide and equipped with communication facilities.

"The tunnels lead to the Tripoli International Airport, the Green Square and a zoo" which is near the hotel where more than 30 international reporters had been detained by the government forces for five days, a rebel fighter said.

After two days of heavy fighting, the rebels captured the Bab Al-Aziziya compound Tuesday. However, the whereabouts of the embattled Libyan leader and his family remain unknown.

A group of rebels besieged several apartment buildings Thursday near the military compound where they said Gaddafi and some of his family members may be holing up, witnesses said.

Heavy gunfire and explosions were heard and thick black smoke were seen near the compound, but whether the rebel fighters could capture Gaddafi has yet to be confirmed.

When Xinhua reporters were trying to enter the tunnels in the military compound, rebels warned that it was dangerous since they hadn't made it clear if there were explosives or Gaddafi loyalists.

"Before 1986, Gaddafi and his family lived in the building," a rebel said, pointing at the bombed apartment behind the giant fist, "But after then he moved into a farm near the airport. Nobody knows where he is now."

Rebels with AK-47 flocked into the compound to celebrate their victory of controlling Gaddafi's command base by firing into the air and painting the fist in red, black and green, the color of the rebel flag.

Near the gate of the compound laid three bodies of government soldiers who were apparently killed days ago. Several meters away is the house of Gaddafi's third son, Saday Mohamed Gaddafi.

The three-layer house has a CD room of more than 20 square meters. Despite Gaddafi's open resentment of the Western culture, the CD room was once filled with western music records and Hollywood film DVDs.

Abandoned pictures of Gaddafi's granddaughter were cluttered on the ground, implying that the family left the compound in a hurry.

The rebels showed Xinhua reporters an escape hole near the bedroom and said almost every building of Gaddafi's family members has such an emergency exit.

Still in hiding, Gaddafi on Thursday called on his supporters to kill the rebels in a four-minute audio message. Meanwhile, with the support of the rebel National Transitional Council, some Libyan businessmen offered a bounty of 1.67 million U.S. dollars for the capture of Gaddafi.