Protesters rally Wednesday in the eastern Libyan town of Derna. The revolt has already broken away nearly the eastern half of Libya and unraveled parts of Moammar Gadhafi's regime.

BENGHAZI, Libya — Army units and militiamen loyal to Moammar Gadhafi struck back against protesters who have risen up in cities close to the capital today, attacking a mosque where many had taken refuge and blasting its minaret and opening fire on others protecting a local airport.

The assaults aimed to push back a rebellion that has moved closer to Gadhafi’s bastion in the capital, Tripoli. The revolt has already broken away nearly the eastern half of Libya and unraveled parts of Gadhafi’s regime.

In the latest blow to the Libyan leader, a cousin who is one of his closest aides, Ahmed Gadhaf al-Dam, announced that he has defected to Egypt in protest against the regime’s bloody crackdown against the uprising, denouncing what he called “grave violations to human rights and human and international laws.”

In the city of Zawiya, 30 miles west of Tripoli, an army unit attacked a mosque where protesters had been camping inside and in a lot outside for several days, calling for Gadhafi’s ouster, a witness said. The soldiers opened fire with automatic weapons and hit the mosque’s minaret with anti-aircraft missiles, he said. Some of the young men among the protesters had hunting rifles.

He said there were casualties, but couldn’t provide exact figures. He said a day earlier an envoy from Gadhafi had come to the city and warned protesters.

The other attack came at a small airport outside Misrata, Libya’s third largest city, where rebels claimed control on Wednesday. Militiamen today attacked residents who were protecting the facility, opening fire with rocket-propelled grenades and mortars, said a resident who saw the assault.

Gadhafi’s crackdown has so far helped him maintain control of Tripoli, a city that holds about a third of Libya’s 6 million population. But the uprising by protesters, backed by army units that joined their ranks, has divided the country and threatened to push it toward civil war.

International momentum has been building for action to punish Gadhafi’s regime for the bloodshed.