TEHRAN, May 26, 2012 (AFP) - Iran has said a new report by the UN atomic energy agency on its nuclear activities is "proof" the programme is peaceful, as analysts played down the agency's discovery of higher-grade uranium traces.

Ali Asghar Soltanieh, Iran's envoy to the International Atomic Energy Agency (IAEA), was speaking late on Friday after the report, circulated earlier in the day, revealed that uranium traces of a higher grade than any found before had been detected.

The report, he said, "is more proof of the peaceful nature of Iran's nuclear activities and of our country's success in the field of nuclear technology, in particular enrichment, and its full cooperation with the agency."

The report, seen by AFP on Friday, said the traces found at the Fordo site, inside a mountain near Qom, were of uranium enriched to purities of 27 percent.

Soltanieh gave no direct reaction to the discovery itself.

"The report once again proves to the international community that all Iranian nuclear activities are successfully underway and are uninterrupted, and that there is no diversion in Iran's nuclear material towards military objectives," he said.

Iran has told the IAEA that the Fordo site was enriching only to 20 percent, which was already of concern to the watchdog since the capability to do so shortens the theoretical time needed to enrich to weapons-grade uranium of 90 percent.

Soltanieh's comments come after the P5+1 powers -- the United States, Russia, China, Britain, France and Germany -- proposed in a meeting with Iran this week that Iran stop 20-percent enrichment and a suspension of all activities at Fordo, diplomats said.

The IAEA report said Iran had indicated that the production of nuclear particles "above the target value" may have happened "for technical reasons beyond the operator's control."

"The agency is assessing Iran's explanation and has requested further details. On 5 May 2012, the agency took further environmental samples from the same location.... These samples are currently being analysed," it said.

Tehran reiterated that on Saturday.

Higher-than-expected traces "are a normal technical issue that is being investigated by (IAEA) experts," Iran's envoy to the IAEA, Ali Asghar Soltanieh, was quoted as telling the official IRNA news agency.

Analysts also played down the discovery of higher-grade traces.

Mark Fitzpatrick, from the International Institute for Strategic Studies think-tank in London, saying it was "probably a technical glitch."

"There are good reasons to worry about Iran's enrichment work but this probably isn't one of them," he told AFP.

The agency's latest report also said satellite imagery showed "extensive activity" at the Parchin military site, which it said could hamper investigating claims of suspected nuclear weapons research there.

The IAEA revealed that its head, Yukiya Amano, wanted in a visit to Tehran on May 21 to "conclude" a deal on clarifying accusations of such research.

But Amano returned empty-handed, saying only that he and Iran's chief nuclear negotiator Saeed Jalili made a "decision" to reach an agreement, and that he expected this to be signed "quite soon."

Mark Hibbs, nuclear proliferation expert at the Carnegie Foundation for International Peace, agreed, also said the IAEA's discovery "isn't proof that Iran is clandestinely enriching uranium to over 20 percent."

Hibbs added, however, that Amano "has to be concerned about that possibility because of Iran's track record of concealment and failure to declare nuclear activities."

Iran has shown that it is loath to curtail its enrichment programme without the prospect that UN and unilateral sanctions imposed on the country in recent years -- more will hit on July 1 -- would be eased.

The P5+1's proposals, made during two days of intense talks in Baghdad, stopped short of this, offering instead a series of lesser incentives that state media reports in Iran indicated Tehran thought were woefully insufficient.

The talks achieved very little other than agreeing to meet again in Moscow on June 18-19.

UN leader Ban Ki-moon said Iran has to build "international confidence" that its nuclear program is peaceful, as he welcomed the commitment to hold new talks.

The UN secretary general "hopes that Iran will take the necessary measures to build and sustain international confidence in the exclusively peaceful nature of its program," his spokesman said.

burs/sma/al