Iran said Sunday it has produced a first batch of uranium yellowcake, the raw material for enrichment, in a move it said "strengthens" its position before talks with world powers on its controversial nuclear programme.

In Washington, the White House said the claim raises "additional concerns" but was "not unexpected" since UN sanctions prevent Iran from importing it.

Iranian atomic chief Ali Akbar Salehi said that the Islamic republic was now "self-sufficient" in the entire nuclear fuel cycle.

"The West had counted on the possibility of us being in trouble over raw material but today we had the first batch of yellowcake from Gachin mine sent to Isfahan (conversion) facility," Salehi said on state television.

Conversion is the process by which yellowcake is turned into uranium hexafluoride (UF6) for enrichment.

"This calls into further question Iran's intentions and raises additional concerns at a time when Iran needs to address the concerns of the international community," White House official Mike Hammer said.

Analysts believe Iran has nearly exhausted 600 tonnes of yellowcake acquired from South Africa in the 1970s before the Islamic revolution, triggering speculation that a lack of raw material might halt its nuclear programme.

A February 2009 study by the US-based Institute for Science and International Security (ISIS) said there was scant evidence at the time that Iran had been able to supplement its dwindling yellowcake supply with domestically mined uranium.

Salehi said Iran still cannot meet "the overall need of the Isfahan facility but... will produce a significant part of it" from Gachin near the Gulf port city of Bandar Abbas.

"Iran has become self-sufficient in the entire fuel cycle, starting from (uranium) exploration, mining and then turning it into yellowcake and converting it to UF6 and then turning it into fuel plates or pellets," he said.

He said Iran would formally notify the International Atomic Energy Agency (IAEA) of its yellowcake production, but declined to disclose the amount of the first domestically produced batch.

The announcement comes as Iran prepares for a new round of talks with world powers on its controversial nuclear programme in Geneva on Monday.

Salehi said it meant Tehran would "go to the negotiations with strength and power."

Uranium enrichment lies at the heart of Western concerns about Iran's nuclear activities as it can produce fuel for nuclear reactors or in highly extended form the fissile core of an atom bomb.

Iran denies seeking nuclear weapons, but has continued enriching uranium in defiance of repeated UN Security Council ultimatums.

A succession of UN sanctions imposed since 2006 aims at preventing Iran from acquiring technology, equipment and raw material for its nuclear programme.

Tehran insists it has a right to enrichment to make fuel as a signatory of the Non-Proliferation Treaty, and has vowed to continue doing so.

"No matter how much effort they put into their sanctions in creating all sorts of hindrance... our nuclear activities will proceed," Salehi said.

The European Union's top diplomat, Catherine Ashton, will conduct the Geneva talks with Iran's chief negotiator Saeed Jalili on behalf of the five UN Security Council permanent members -- Britain, China, France, Russia and the United States -- plus Germany.

President Mahmoud Ahmadinejad has repeatedly insisted that enrichment is "non-negotiable" while calling on Western governments to "stop being hostile."

Iran also accuses Western powers and Israel -- the sole if undeclared nuclear power in the Middle East -- of being behind the recent assassination of a top nuclear scientist and of seeking to sabotage its nuclear programme.

Interior Minister Mostafa Mohammad Najjar said that some people behind the assassination and other attacks on nuclear scientists had confessed to Israeli involvement.

"We are pursuing the arrest of all the perpetrators of these attacks, some of whom have been captured," the English-language Press TV website quoted Najjar as saying.

"He added that according to the confessions of the arrested suspects the role of Israel in the incidents is completely obvious."

It took Iran and the six powers a month to agree on a date and venue for the Geneva talks, but they have yet to agree on an agenda.

The world powers want the talks to focus on Iran's enrichment programme, but Tehran wants a wider discussion including regional security issues and Israel's suspected nuclear arsenal.

burs/srm