Iran "will never stop" its controversial uranium enrichment, the country's envoy to the IAEA said on Tuesday, on the sidelines of a Non-Aligned Movement ministerial meeting in Tehran.

"Our enrichment activities will never stop and we are justified in carrying them out, and we will continue to do so under IAEA supervision," Ali Asghar Soltanieh told reporters.

"We will not give up our inalienable right to enrichment," he said.

The defiant reaffirmation of Iran's position underscored a showdown between the Islamic republic and the UN's International Atomic Energy Agency, and the UN Security Council.

The Security Council has repeatedly demanded Iran cease its uranium enrichment and has imposed four sets of sanctions on the country, which have been greatly reinforced by separate US and EU sanctions.

The five permanent members of the Security Council, plus Germany, also this year engaged in three rounds of face-to-face negotiations with Iran on the issue, but they ended in an impasse, with contact downgraded to telephone calls between Iranian and EU officials.

Iran's enrichment is to again be raised this week, when the IAEA is expected to release its latest report based on its ongoing inspections of Iran's nuclear facilities.

Some of the report's findings have already been leaked to Israeli and US media, mainly those confirming a July 25 statement by President Mahmoud Ahmadinejad that hundreds more uranium enrichment centrifuges had been installed.

Iran's refusal to allow inspectors into a military base outside Tehran, Parchin, could also form part of the report.

Western diplomats last week told AFP that months of clean-up work detected at Parchin suggested the site had been "sanitized" to such an extent that a nuclear inspection would now be pointless.

Soltanieh responded by saying that Parchin "has been blown out of proportion" and said claims of nuclear warhead design tests there were "fabricated by foreign intelligence."

He said Iran was demanding to see the documents the IAEA was using to pursue its suspicions about Parchin and urged the agency to "close this chapter."

He also said Iran has complained to the IAEA about the leaks.

On Iran's intent to continue enriching uranium, Soltanieh noted that the nuclear Non-Proliferation Treaty and the IAEA's statutes made no explicit mention of levels of enrichment.

"The level of enrichment and how much to enrich has not been fixed in either of those. There is no limitation," he said.

"Everything we do is under the supervision of the agency," he stressed.

The United States and its Western allies, and Israel, suspect that Iran is intent on developing nuclear weapons "break-out" capability.

Iran denies that, saying its nuclear programme is purely for civilian use.