TEHRAN - Iran will announce unspecified new "nuclear achievements" if the United Nations takes fresh steps against it over its disputed atomic program, President Mahmoud Ahmadinejad said on Monday.

Iran's President Mahmoud Ahmadinejad points to his supporters as he speaks at a sport complex in the city of Shiraz, 895km (556 miles) south of Tehran April 16, 2007. [Reuters]

"If they (the United Nations) pass another resolution against Iran, our nation will reveal new nuclear achievements," Ahmadinejad told a rally in the central province of Fars, the official IRNA news agency reported.

Defying a UN demand to halt uranium enrichment, Iran said last week it was capable of industrial-scale enrichment, a process the West fears Tehran will use for bomb-making. Iran denies this, saying its aim is to produce electricity.

The announcement prompted the United States to say it was likely the UN Security Council would impose further penalties against Tehran.

In Iran's first public reaction to the US warning, Ahmadinejad had earlier accused world powers of using international organizations like the UN for their own ends and said Iran would not give up its right to nuclear technology.

"The Iranian nation will stand up for its legal right and will not retreat even one iota to preserve its nuclear right," Ahmadinejad said in a televised speech to a rally in the central Iranian city of Shiraz.

The crowd chanted "Death to America," and "Nuclear technology is our right."

Ahmadinejad is not the most powerful figure in Iran's system of rule which gives the final word on policy, including nuclear affairs, to Supreme Leader Ayatollah Ali Khamenei.

But the president is often the most prominent voice both inside Iran and abroad because of his fiery and usually anti-Western speeches made on regular tours of the country.

"BULLYING METHODS"

The Security Council in March imposed a second round of sanctions on Iran for refusing to halt enrichment work, banning Tehran's arms exports and putting financial bans on individuals and institutions. That resolution followed one in December.

Ahmadinejad said Iran would not yield to international pressure, calling on the West to give up its "bullying methods."

"Abandon your oppressive behavior. Otherwise you (the West) and your nations will be harmed," Ahmadinejad said, without elaborating.

Iran has threatened, if pressured, to review its membership of the nuclear Non-Proliferation Treaty, the accord that obliges non-nuclear states to renounce the pursuit of atomic weapons.

Iran said on Sunday it would seek bids in the next few days for two new nuclear power plants and will partly run them on fuel produced at home.

Some Western diplomats and analysts say the move was to justify Iran's insistence on producing its own atomic fuel. Western experts say it would be cheaper for Iran to import fuel, but Tehran says it needs the security of domestic production.

The two new power plants would be built at Bushehr, the southwest port city where Russians are building Iran's first atomic plant.