Ahmadinejad, 49, an ultra-conservative former revolutionary guard, was formally installed at a ceremony led by supreme leader Ayatollah Ali Khamenei after coming from nowhere to win a stunning election victory in June.

In his first address, the new president appealed for an end to weapons of mass destruction in the world a day after the West issued sharp warnings to Tehran over its threatened violation of a deal suspending its nuclear programme.

But after formally endorsing Ahmadinejad as president, Khamenei ordered the new government not give up "the rights of the nation."

"Iranian leaders have no right to give up the nation's economic and political rights. These rights must be defended," Khamenei said in a speech punctuated by cries of "Death to America, Death to Israel" from regime officials at the ceremony.

"I congratulate the Iranian people for their vote, I confirm that vote and name Mr. Ahmadinejad president of the Islamic Republic of Iran," Khamenei said in a declaration read by outgoing reformist President Mohammad Khatami.

The European Union and United States on Tuesday issued sharp warnings to Tehran over its threats to resume some sensitive nuclear fuel work, risking an international crisis.

In his address following the ceremony attended by regime leaders and foreign ambassadors, Ahmadinejad said: "I will plead for the suppression of all weapons of mass destruction.

"Iran wants to see the establishment of last peace and justice," Ahmadinejad said. "I will work for international justice because the world is starved of justice."

"As servant of the Iranian nation, I want to defend its independence, our national interests and the religion of Islam. I want to defend the interests of citizens both inside and outside the country," he said.

"I wish to extend justice, to be good to all God's subjects, to serve the people of Iran, to offer them progress and financial prosperity."

He pledged to pay "special attention to the disadvantaged," in a speech that also paid homage to the founder of the Islamic republic Ayatollah Ruhollah Khomeiny, to the "martyrs of the revolution" and veterans of the war with Iraq.

It was the first indication from Ahmadinejad of how Iran will look under his rule. The first non-cleric to hold the post since 1981, he is Iran's sixth president since the revolution and will serve a four-year term.

Branded by his enemies before his landslide June 24 victory as a dangerous extremist, the former revolutionary guard has gone out of his way to vow there will be "no place for extremism" in his government.

Ahmadinejad has pledged to extend "the hand of friendship" to the international community, and made clear that he is ready to work with any country that does not show animosity to Iran.

But many diplomats and rights groups doubt he will show more conciliation with dissidents or the international community than did the previous administration of Khatami, whose efforts at reform were stymied by hardliners.

Any thoughts a rapprochement with arch enemy the United States could be on the horizon have already been buried by Ahmadinejad's assertion Iran is strong enough without Washington along with accusations he took part in the 1979 kidnapping siege at the US embassy in Tehran.

But what reaped Ahmadinejad 61.69 percent of the votes in his crushing run-off win against regime veteran Akbar Hashemi Rafsanjani was his success in convincing Iranians he is an honest Muslim who cares about their economic problems.

Iranians who are more concerned with their weekly pay packets than freedom of the press will be looking to the man who proudly presents himself as the "nation's street sweeper" to put money into their pockets.

He may be helped by a bumper oil revenues in the current financial year -- 24.4 billion dollars more than budgeted -- thanks to the current high oil prices.

Having initially alarmed economic observers by promising to thwart a "mafia" that was dominating the oil industry and promising a redistribution of wealth, Ahmadinejad has moved to calm nerves by saying that he is pro-investment.

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