ISLAMABAD, June 5 : The Pakistan Air Force (PAF) has been forced to suspend a plan to rebuild the engines of its F-16 aircraft due to the suspension of US aid, Defense Minister Abdul Majid Malik said Tuesday, reports AFP.

The Minister told parliament that Pakistan had launched a project to rebuild engines of the lighter bombers domestically but the plan has been withheld because Washington has refused to provide crucial equipment and expertise.

There were certain difficulties in the purchase of its spare parts, he added, stressing that the PAF had not yet been forced to ground its F-16s.

The PAF acquired 40 F-16s in 1987 after the United States lifted its several year old aid freeze in 1981 in the wake of the Soviet invasion of neighbouring Afghanistan.

In June 1989 then Premier Benazir Bhutto secured US approval for the purchase of 60 more of the high-tech warplanes, built by general dynamics.

But deal failed to materialise after Washington in October 1990 halted its estimated 600 million dollars in annual economic and military assistance on suspicions that Pakistan was seeking to develop nuclear weapons.

Pakistan has Insisted that its nuclear programme is peaceful.