Iran's president stood fast Saturday behind his decision to resume uranium enrichment research, shrugging off threats of international sanctions while his Foreign Ministry invited Europe and the U.N. nuclear watchdog back to the negotiating table.

In a ringing defense of his government's move, President Mahmoud Ahmadinejad said Tehran had not violated the Nuclear Nonproliferation Treaty, which he said allows signatories to produce nuclear fuel.

On Tuesday, Iran removed some U.N. seals from its main uranium enrichment facility in Natanz, central Iran, and resumed research on nuclear fuel — including small-scale enrichment — after a 2 1/2-year freeze.

The shift alarmed Western nations that suspect Iran may be trying to produce nuclear weapons. Uranium enrichment can produce fuel for nuclear reactors to generate electricity or, if sufficiently processed, the material for nuclear warheads.

Tehran claims it is only conducting research and says uranium enrichment remains suspended.

But its decision drew fierce international condemnation and threats to seek U.N. sanctions.

"The time of using language of bullying and coercion ... is over," Ahmadinejad said at a news. "There is no evidence to prove Iran's diversion (toward nuclear weapons)."

What's more, he said, Iran had no use for such weapons.

"Our nation doesn't need nuclear weapons. You can use nuclear technology in several ways, and we want to do so peacefully," he said, claiming that such weaponry violated the tenets of Islam.

Iran insists its nuclear program is intended only for electricity generation.

Ahmadinejad's news conference came on the second day of a tough public relations offensive by Tehran. On Friday, it threatened to end surprise inspections by and cooperation with the International Atomic Energy Agency if the country is referred to the Security Council for possible imposition of sanctions.

Europe and the United States have been trying to build support for the move. They say more than two years of acrimonious negotiations between Iran and the European powers Britain, France and Germany reached a dead end when Iran resumed work at the enrichment facility.

But they face resistance from China, which warned the move could only escalate the confrontation. China is highly dependent on Iran for oil.

Russia, which like China holds a veto on the Security Council, is a question mark as well. It is deeply involved in building Iranian reactors for power generation and has in the past indicated it would not support sanctions.

"The world public opinion knows that Iran has not violated the Nonproliferation Treaty," Ahmadinejad said. "There are no restrictions for nuclear research activities under the NPT protocol, and Iran has not accepted any obligation (not to carry out research). How is it possible to prevent the scientific development of a nation?"

But Iran's foreign ministry made an apparent attempt to calm tensions, calling for resuming talks with the European Union and cooperation with the U.N. nuclear watchdog.

"Iran is ready to cooperate with the IAEA to clear ambiguities," a foreign ministry statement quoted on state television said.

And Ahmadinejad said: "We have always wanted dialogue."

"I recommend to them (the West) to try to understand the Iranian nation and government. Otherwise you may do something that will make you regret it," he added.

Ahmadinejad charged that the threats of sanctions and Security Council action were the true dangers to world stability, not Iran's nuclear program.

"Why are you employing the Security Council? Doesn't that endanger world security?" he said.

Ahmadinejad said the presence of IAEA surveillance equipment at Iranian nuclear facilities is proof that Iran has nothing to hide.

"How will world public opinion accept their propaganda campaign against Iran when IAEA cameras are installed on all nuclear sites?" he asked.

He said Iran had spent 2 1/2 years trying to win the trust of the international community, citing its agreement to seal some research sites, allow surprise IAEA inspections and impose a moratorium on uranium enrichment.

"Now, it is the turn of the European countries to apply trust-building measures," he said.