Mohamed ElBaradei, director of the International Atomic Energy Agency, said the world shouldn't "jump the gun" with erroneous information as he said the US-led coalition did in Iraq in 2003, nor should it push the country into retaliation as international sanctions did in North Korea.

"Our assessment is that there is no immediate threat," the winner of the 2005 Nobel Peace Prize told a forum organised by the Monterey Institute of International Studies south of San Francisco. "We still have lots of time to investigate."

"You look around in the Middle East right now and it's a total mess," he said. "You can not add oil to that fire."

The recent violent history in Iraq bears an important lesson for diplomacy with neighbouring Iran, the diplomat said. "We should not jump the gun. We should be very careful about assessing the information available to us," he said.

The Bush administration led a coalition into Iraq in 2003 saying President Saddam Hussein was developing weapons of mass destruction. No such weapons were found.

"I ask myself every day if that's the way we want to go in getting rid of every single dictator," ElBaradei said.

While it was unclear whether Iran ultimately intended to redirect its development of nuclear power into a weapons system, it was clear there was no danger of that right now, he said.

The five UN Security Council permanent powers and Germany, trying to curb Tehran's nuclear programme, are planning to meet in Vienna on Thursday to try to finalise a package of incentives for Iran to halt uranium enrichment along with penalties if it keeps defying international pressure.

ElBaradei said he believed a majority in the Iranian leadership was still interested in a negotiated solution and normal relations with the world. The United States is pressing for tough UN sanctions if Iran does not comply.

"It would be terrible" to try to strengthen sanctions, which could force Iran to retaliate, he said.

"We have learned some lessons from North Korea," he said. "When you push a country into a corner, you are giving the driver's seat to the hard-liners there."