Iran says nuclear drive unstoppable

A defiant Iran vowed to expand its nuclear programme after making a crucial advance in the fuel cycle that triggered global condemnation and could risk UN sanctions.

World powers were scrambling to find consensus on how to contain Iran's nuclear activities as the head of the UN atomic watchdog arrived in Tehran in a fresh bid to resolve the escalating crisis.

Iran was basking in national pride after regime scientists successfully enriched uranium to make nuclear fuel -- a milestone in its atomic drive -- and officials pledged to move rapidly to industrial-scale work.

The international community united in condemning the move although differences remain over what should happen next, with Washington demanding "strong steps" from the UN Security Council and Russia warning against the use of force.

Representatives of the five permanent members of the Council plus Germany are to meet in Moscow next Tuesday to discuss the crisis, China's UN envoy said.

Iran's announcement is also a blow to International Atomic Energy Agency director Mohamed ElBaradei, who arrived in Tehran overnight for talks with the regime's top nuclear negotiator.

"We hope to convince Iran to take confidence-building measures including suspension of uranium enrichment activities until outstanding issues are clarified," ElBaradei told journalists at the airport.

"I would like to see Iran has come to terms with the request of the international community."

ElBaradei said that depsite the escalation in tensions he hoped the nuclear crisis still could be resolved through political dialogue.

"I am hopeful the time is right for political solutions, through negotiations. I hope conditions will be created for all parties to return to talks," he said.

ElBaradei must give a report at the end of April on Iran's nuclear activities to the UN Security Council and the 35 states of the IAEA's governing council.

The United States accuses Iran of seeking to secretly build nuclear weapons, charges denied by OPEC's number two oil exporter which insists the drive is aimed purely at electricity generation.

The Security Council has set April 28 as a deadline for Tehran to halt the ultra-sensitive uranium enrichment, a process which can be extended to make the fissile core of a bomb.

Iran's armed forces joint chief of staff, General Hassan Firouzabadi, was in no mood to back down. "When a people master nuclear technology and nuclear fuel, nothing can be done against them," he said.

"The West can do nothing and is obliged to extend to us the hand of friendship," the ISNA news agency quoted Firouzabadi as saying.

US Secretary of State Condoleezza Rice called for the 15-member Security Council to take "strong steps" and the White House said sanctions were now an option.

"It's time for the Security Council to act on the diplomatic front," said White House spokesman Scott McClellan.

"There are a number of options that are available to us through the diplomatic process," he said, adding that officials were nonetheless still "pursuing a diplomatic solution".

ElBaradei has said "the jury is still out" over the true nature of Iran's programme and is also trying to press Iran to agree to a fuel cycle moratorium while his frustrated investigation continues.

Officials from permanent Security Council members Britain, France and Russia, and Germany, all said Iran had taken a "step in the wrong direction".

Russian Foreign Minister Sergei Lavrov was however quoted as strongly opposing the use of force after US reports over the weekend suggested Washington was considering military action -- even a possible nuclear strike.

"I am convinced that there can be no resolution of the problem through use of force... practically all European countries are in solidarity with Russia," he said.

But Israeli military chief of staff General Dan Halutz described a nuclear Iran as "a threat to the whole world and not only Israel".

The Jewish state -- believed to be the only nuclear armed state in the region -- views the regime in Tehran as its number one enemy, alarmed in particular by a call last year from Ahmadinejad for Israel to be "wiped off the map" as well as his dismissal of the Holocaust as a "myth".

Ahmadinejad repeated his call on foreign governments to "recognise and respect Iran's rights" and has urged an acceleration of enrichment work.

Iran's nuclear milestone was achieved on Monday -- at a pilot plant of 164 centrifuges in Natanz -- with uranium enriched to 3.5 percent, the purity required for civilian reactor fuel.

This, said Iranian vice president and atomic energy chief Gholam Reza Aghazadeh, "paves the way for enrichment on an industrial scale".

He also said Iran was "determined" to complete work within three years on a heavy water reactor in Arak -- which critics say which could also produce plutonium for a nuclear weapon.