Explosions and heavy gunfire rocked Tripoli late Saturday as the Libyan government denied that the rebels were advancing toward the capital — Libyan leader Moammar Gadhafi's last main stronghold.
Government spokesman Moussa Ibrahim said small groups of armed rebels infiltrated the city but have been dealt with and the city is now calm.
The reports of fighting in Tripoli came hours after the rebels reportedly seized control of two strategic towns — Zawiya in the west and Brega in the east.
In Zawiya, the rebels said they were now occupying positions formerly held by pro-Gadhafi forces, who continued shelling the city from the east.
A senior rebel commander said Saturday his fighters were also in full control of the eastern town of Brega after seizing its industrial sector, which also contains a major oil refinery. However, the claim could not be verified independently.
Fighting spilled across the border into Tunisia, where clashes erupted late Friday between Tunisian troops and a group of Libyans traveling in vehicles with weapons. Tunisian forces reported several casualties, but did not say whether the fighters were Libyan rebels or pro-Gadhafi soldiers.
Mr. Gadhafi has seen the areas under his control shrink significantly in recent weeks as rebels advance on Tripoli from the west, east and south after six months of fighting to end his four-decade autocratic rule.
NATO warplanes have been supporting the rebels by bombing pro-Gadhafi forces to enforce a U.N. Security Council resolution authorizing military action to protect Libyan civilians from government attacks.
Meanwhile, two more Gadhafi aides appear to have defected to the rebel side. Tunisian officials said the Libyan leader's former number-two, Abdel-Salam Jalloud, departed from the Tunisian island of Djerba on a flight to Italy Saturday. A day earlier, Libyan rebels said Jalloud, a former prime minister, had joined their ranks.
Tunisian officials also said Libyan Oil Minister Omran Abukraa has decided not to return to Libya after a recent mission to Italy. A Tunisian official told the Reuters news agency that Abukraa was in Tunisia.