VIENNA, March 11: United Nations nuclear inspectors have found in Iran traces of uranium enriched up to 80 per cent, a weapons-grade level, but think this is from contamination of imported equipment rather than refined in Iran, a diplomat close to the UN atomic agency told AFP on Thursday.

He was commenting on a report in The New York Times which said inspectors of the International Atomic Energy Agency (IAEA) had found traces of uranium "enriched to 90 per cent of the rare 235 isotope".

But the diplomat said the actual enrichment rate was lower, "up to 80 percent", and that these were highly enriched uranium particles which the IAEA has already reported, without mentioning the level of enrichment, in reports issued in November and February.

The highly enriched uranium (HEU), which is refined in large groups of gas centrifuges, can be used both in research reactors for peaceful purposes or as raw material for the bomb. But the diplomat stressed that the amount found was microscopically small. 1Experts say some 21kg of U-235 enriched to over 80 per cent are needed to make an atomic bomb.

"There is no quantity, absolutely, only individual particles," the diplomat, who asked not to be named, said. "The particles were found on imported equipment, centrifuges," the diplomat said.

The IAEA had reported in November that its inspectors had found in "environmental samples . . . the presence of high enriched uranium (HEU) particles and low enriched uranium (LEU) particles which were not consistent with the nuclear material in the declared inventory of Iran."

These were found at the Kalaye Electric Company near Tehran and the Natanz fuel-making facility in the south of the country. There was no proof that this HEU was used in weapons research, the report said.

The Iranians claimed that the HEU had come from contaminated imported equipment, some of which might have come from Pakistan which had nuclear weapons, and thus would have uranium enriched to extremely high levels, the diplomat said.

IAEA officials have told AFP they have not yet determined whether the enriched uranium found in Iran was made by Iranians, came from contaminated equipment or came from HEU bought by the Iranians on the nuclear black market.

"The likelihood is that this input is from contamination from imported equipment," the diplomat said. "That is today the most credible explanation," he said. -Reuters