Pakistan has reduced the number of nuclear-capable F-16 fighter jets it planned to buy from the United States, from 36 to 18, due to financial constraints.

The original plan envisaged Pakistan acquiring 36 jets under a 5.1 billion-dollar package that would have included weapon systems and spares as well as upgrading the earlier fleet of F-16s bought in the 1980s.

The 36 new F-16 block 50/52 jets were to have cost Pakistan three billion dollars and the weapon systems an additional 650 million dollars.

The decision to reduce the order by half would also halve the cost of the proposal to buy new F-16s and weapon systems, Dawn newspaper quoted diplomatic sources as saying on Wednesday.

Pakistan, however, will still have to spend 1.3 billion dollars on the mid-life upgrade and modification of its older F-16 A/B jets. Engine modification and the purchase of some new equipment for the old fleet will cost an additional 151 million dollars.

The new Pakistan government is currently facing a major financial crunch due to rising global oil prices and inflation. Leaders of the ruling coalition have hinted at a cut in the defence budget due to the financial crisis.

The sources said that the new jets will be fully equipped with the weapons and equipment that come with an F-16 Block 50/52 jet. These aircraft will be capable of carrying nuclear and non-nuclear weapons.

"The media stories that the new aircraft will not have the facility to carry a nuclear weapon do not make sense," said a defence expert.

He pointed out that the French Mirage jets operated by the Pakistan Air Force did not have such facilities when they were purchased. Pakistan modified the jets to make them nuclear-capable, he added.

The US will have the right to conduct frequent inspections and inventory checking of the new jets, the diplomatic sources said.

Pakistan's request for new F-16s and for the modification for its older fleet was put on hold after the October 2005 earthquake.