"There were four explosions at the air force base alongside the international airport and two fighter jets went up in flames," the official said on condition of anonymity.

Residents of the area reported loud explosions and massive flames and plumes of smoke.

There were no immediate reports of casualties.

Meanwhile, four people, including three children, were killed overnight when troops loyal to Yemeni President Ali Abdullah Saleh shelled a petrol station in a region north of the capital, tribal sources said on Sunday.

Thirteen others were wounded in the attack in the Arhab area, some 40 km from Sanaa, where tribesmen have backed protesters demanding an end to Saleh’s 33-year rule.

In the city of Taiz, a doctor said one civilian was shot dead and two were wounded by government forces who fired at a car. The incident occurred in a district where there have been clashes between government forces and pro-opposition tribesmen.

Meanwhile, a Yemeni policeman was killed Sunday and three others were wounded in a bomb attack on their vehicle in the southern port city of Aden, a security official said.

“An explosive device was planted in a police car on a routine patrol... 200 meters from Aden’s airport,” the official said, adding that the driver of the vehicle was killed and three other policemen were wounded in the attack.