ISLAMABAD, June 30: Two mystery ‘blasts’ which shook the federal capital and Rawalpindi on Monday morning, sparking fears of a terrorist strike, were caused by a sonic boom from a Pakistan Air Force fighter jet when it broke the sound barrier.

The effect of ‘blasts’ was felt all over the country and also shook the stock market for some time because of the volatile security situation in the country and confusion caused by a delay in explanation by the authorities about the cause.

The explosions heard at about 11am, rattled windows and alarmed people and security agencies which have witnessed a spate of suicide attacks by militants in recent days.

Emergency services were placed on alert and police combed the area.

Edgy news channels flashed news of explosions adding to the panic. The PAF at first denied that its jets might have caused the sonic boom, but hours later the PAF directorate of public relations said an F-7P fighter aircraft had broken the sound barrier over Pindigheb, a town 55 miles south-west of the capital, producing the sonic boom that was mistaken for explosions.

“An F-7P fighter aircraft, while on a scheduled functional control flight mission, crossed the sound barrier in Pindigheb area,” the statement said.

The fighter aircraft flew a planned ‘maintenance check mission’ after an overhaul at the Pakistan Aeronautical Complex in Kamra.

The PAF spokesman said: “The aircraft was transiting from 40,000 feet altitude to 15,000 feet.”

The sonic boom waves, the spokesman said, travelled to adjacent areas due to high altitude and clear weather.

Fighter pilots are prohibited to break sound barriers over populated areas, but a PAF spokesman claimed the pilot had crossed the barrier while flying over a barren area.