Mohamed ElBaradei, head of the International Atomic Energy Agency (IAEA), told CNN Sunday that he had no evidence Iran was building nuclear weapons and accused US leaders of adding "fuel to the fire" with their warlike rhetoric.

"He will say what he will. He is the head of a technical agency," US State Department spokesman Sean McCormack told reporters. "I think we can handle diplomacy on this one."

"We appreciate the work that the IAEA is performing but it is the member states of the international community that are going to be responsible of the diplomacy with respect to Iran and its nuclear program," said McCormack.

At the White House, spokeswoman Dana Perino said there was no doubt about Iran's plans because "this is a country that is enriching and reprocessing uranium and the reason that one does that is to lead towards a nuclear weapon."

Uranium enrichment and reprocessing produces fuel for nuclear reactors, but can also be a key step to creating the core of an atomic bomb. Iran says it wants a civilian energy program, not an atomic arsenal.

Asked whether any country enriching uranium seeks nuclear weapons, US National Security Council spokesman Gordon Johndroe clarified Perino's remarks.

"I would say that we're concerned about Iran doing this because they could have the capability to have a nuclear weapon. Each country is different, but obviously Dana was asked and was talking about Iran," he said.

Iran's leaders have repeatedly said they will never suspend enrichment, in flagrant defiance of repeated UN Security Council resolutions calling on Tehran to suspend the process.

"We have put on the table for Iran a path for them to get a civil nuclear program. And all they have to do to get there is to suspend its enrichment of reprocessing of uranium and they can come to the table and we can have a further discussion," said Perino.

"It's the Iranians who have decided not to be at that table," she said.

The United States has sharply escalated its rhetoric against the Islamic Republic, while slapping a new set of sanctions on its Revolutionary Guards, accused of spreading weapons of mass destruction, and its elite Quds Force, which was designated as a supporter of terrorism.

"Iran is the largest national security challenge we have in regards to nuclear weapons today," said Perino, who contrasted Tehran's approach to North Korea's agreement to dismantle its nuclear weapons program.

"We are in discussions with North Korea, through the six-party talks, and that is because North Korea agreed to give up its weapons and make a full declaration of activities that they've been pursuing," she said.

She was referring to negotiations grouping China, Japan, Russia, North and South Korea and the United States, and a deal offering Pyongyang economic and diplomatic rewards if it gives up it nuclear weapons program.

"Iran could have the same option, but they've chosen not to," the spokeswoman said.

related report
China's Wen to talk to Russia over Iran's nuclear drive
Chinese Premier Wen Jiabao will raise the Iranian nuclear issue with Russian President Vladimir Putin during a visit to Moscow early next month, China's foreign ministry said Monday.

Assistant Foreign Minister Li Hui reiterated China's position that diplomacy is the right approach to ending the dispute over Iran's controversial nuclear programme.

"We believe resolving the Iranian nuclear issue through diplomatic negotiations is the best way," Li said at a press briefing when discussing the the message Wen will deliver during his state visit to Russia on November 5-6.

"China hopes Iran can cooperate closely with the international community... and we hope relevant parties will exercise restraint and patience and seek a long-term and proper solution to the Iranian nuclear problem."

Li's comments came as Israeli Foreign Affairs Minister Tzipi Livni was in China for talks with officials about Iran.

Her meetings in Beijing are expected to focus on potential further UN sanctions that could be applied if Tehran fails to halt uranium enrichment, which the West fears is a cover for atomic weapons development.

Iran strongly denies claims it is attempting to develop nuclear arms.

Washington announced unilateral sanctions against three banks and several units of the Iranian military last Thursday -- a move that China said would only complicate the issue.

Wen will also discuss with Russia the two countries' energy ties and a series of bilateral agreements will be signed according to Li.

Wen's visit will be part of a five-day trip to member states of the Shanghai Cooperation Organisation between November 2-6, during which he will also visit Uzbekistan, Turkmenistan and Belarus.