"On Iran, there has been very little progress," the official said, speaking on condition of anonymity. "And for Syria, it's the same thing."

Iran was still defying the UN Security Council and has so far amassed 1,339 kilogrammes of low-enriched uranium hexafluoride (UF6), the International Atomic Energy Agency said in a restricted report, a copy of which was obtained by AFP.

Estimates vary, but analysts calculate that anywhere between 1,000-1,700 kilogrammes of low-enriched uranium would be needed to convert it into highly-enriched uranium suitable to make a single atomic bomb.

"Iran has estimated, that between November 18, 2008 and May 31, 2009... a total 500 kilogrammes of low-enriched UF6 was produced" at its enrichment plant in Natanz, the IAEA said.

Prior to that, Iran had already amassed 839 kilos of low-enriched UF6.

The IAEA insisted that all of the UF6 and all installed cascades "remain under agency containment and surveillance" and that none of the declared nuclear material had been diverted.

But Iran's ambassador to the IAEA, Ali Asghar Soltanieh, told the Fars agency Friday that Tehran would not suspend its nuclear activities.

In all, more than 7,000 uranium-enriching centrifuges were installed at Natanz, up from over 5,000 at the time of the IAEA's last report in February, the watchdog said.

As of the end of May, 4,920 centrifuges were actively enriching uranium; 2,132 centrifuges were installed and undergoing dry-run tests; and a further 169 machines installed, but not spinning.

The UN Security Council has ordered Iran to suspend all enrichment related activities, until the IAEA has been able to verify the exact nature of Tehran's controversial nuclear programme.

Western powers fear that Iran wants to build an atomic bomb, but Tehran insists it merely aims to produce civilian nuclear energy.

There were still "a number of outstanding issues which give rise to concerns, and which need to be clarified to exclude the existence of possible military dimensions to Iran's nuclear programme," the IAEA stated.

But there "has been practically no communication" between Tehran and the agency on those issues for months now, the official said.

Iran was refusing to allow more pervasive inspections, as allowed under the so-called Additional Protocol, and was stonewalling requests for access to "information, documentation, locations and individuals," the IAEA complained.

"It's a stalemate," the official said.

In a separate report on Syria, the IAEA said its inspectors found uranium particles at a research reactor near Damascus that would not normally be expected there and had asked Syria to explain how they got there.

Inspectors had found "anthropogenic natural uranium particles in environmental samples taken in 2008 from the hot cells of the Miniature Neutron Source Reactor (MNSR) facility in Damascus," the report said.

It was not the type of uranium that would normally be expected to be found at this kind of reactor, a senior official close to the IAEA said on condition of anonymity.

The IAEA has been investigating allegations of illicit nuclear work by Syria since last year.

The United States alleges that a remote desert site -- known alternatively as Dair Alzour or Al-Kibar -- was an undeclared nuclear reactor until it was bombed by Israeli planes in September 2007.

The IAEA has said that the building bore some of the characteristics of a nuclear facility and UN inspectors had also detected "significant" traces of man-made uranium at that site, too, as yet unexplained by Damascus.

But it was too early to say whether the uranium particles at Dair Alzour were connected in any way to those found at the research reactor, the official said.

Syria has claimed the uranium at Dair Alzour came from the Israeli bombs, but the watchdog has more or less ruled out that interpretation.

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