After the complaints, Pakistan's Ministry of Defence asked the US Secretary of Air Force International Affairs,  which is the coordinator and supervisor for the project, to extend the signing of LOA until December 31, reports The Friday Times, a Pakistani weekly.

The last extension was sought on July 31 this year.

The deal was apparently deferred partly due to conditions imposed by the US on the operations of F-16s and the "absence" of vital electronic capabilities from these platforms. Musharraf was expected to take up these issues when he meets President George W Bush [Images] in Washington today.

"So the signing deal is off. Perhaps President Musharraf will try to extract some concessions during his meeting with Bush. But the entire deal is likely to spark much more debate and change before finalisation," the weekly quoted a Pakistani official as saying.

According to the report, the F-16s were being offered without some Electronic Warfare programme capabilities for their radar warning receiver (RWR). "This means that they will have pre-installed threat library and its RWR will only be able to identify Non-NATO aircraft," it quoted an expert as saying.

"Any NATO aircraft attacking these F-16s using Beyond Visual Range capability could take them out easily simply because these F-16s would not know when they would be locked in sight of the attacking adversary and hence would be unable to take evasive measure," he said.

However, PAF Chief Air Marshal Tanvir Ahmed denied reports that there was any bar on operational deployment of F-16s being purchased at the cost of about five billion dollars from the US.

Ahmed said US authorities have not imposed any conditions on operational capability. "We will be fully empowered to use our platforms whenever we want and however we want," he told The News.

He said the Pakistan Air Force would use the F-16s for all sorts of offensive and defensive sorties carrying conventional weapons. Earlier reports said US has excluded the equipment necessary to carry nuclear weapons from the package being offered to Pakistan.

As for "arrival" of US personnel at the bases where the F-16s are going to be placed, he said it was not something surprising or new. US personnel had also come along when Pakistan bought F-104 Starfighters in 1960 and F-16s in 1983. The same was true of France [Images] and China, who sent their personnel to provide PAF technical assistance during early days.

The US does not want to transfer technology to any other country, specially countries with which Pakistan had defence cooperation, he said without directly referring to China.

The Friday Times report said that US was concerned about transfer of technology to China as Beijing [Images] is considered to be an expert in reverse engineering. Pakistan and China are currently developing JF-17 Thunder aircraft.

More reports from Pakistan