ISLAMABAD, Feb 27: Pakistan on Friday strongly rejected news reports that it had conducted joint nuclear tests with North Korea and dismissed it as a "wild, mischievous and irresponsible speculation".

According to APP, foreign office spokesman Masood Khan, when asked about a report published by the New York Times on Friday, said: "This news report is incorrect and fallacious. We take it as no more than wild, mischievous and irresponsible speculation."

He said Pakistan had conducted its nuclear tests in 1998 exclusively by indigenous means which, he said, was a matter of pride for the people of Pakistan.

"The fanciful conjecture that it might have been a 'joint test' is a mere fantasy, nothing more," Mr Khan added. He said Pakistan did not have nuclear cooperation with any country. "The government of Pakistan has had no interaction with North Korea in the nuclear field. None whatsoever," he said.

The NYT report, according to our correspodent, said: "Startling clues were detected after underground tests that Pakistan carried out in May 1998, when it proved to the world that its own efforts to build nuclear weapons had succeeded.

According to former and current American intelligence officials, an American military jet sent to sample the air after the final test in the wastelands of the Balochistan desert picked up traces of plutonium."

That surprised experts at the Los Alamos national laboratory, because Pakistan said openly that all of its bombs were fuelled by highly-enriched uranium produced at Dr Khan's laboratories, the newspaper said.

Among the possible explanations hotly debated after the tests was that North Korea "perhaps in return for the help from Dr Khan" might have given Pakistan some of its precious supply of plutonium to conduct a joint test of an atomic weapon.

The debate over the 1998 tests was never settled and fell into obscurity, until Dr Khan confessed last month that he had spread nuclear skills and equipment over more than a decade.