But Iranian national security chief Ali Larijani also said the Islamic republic was open to new negotiations with the United States over restoring stability to Iraq following landmark talks last month.

"We are an oppressed power in the region, and we are not pursuing adventurism," Larijani, who is also Iran's top nuclear negotiator, said in an interview with Newsweek magazine.

The Iranian official said his Shia Islamic country was arming neither Iraqi militias nor the Sunni Muslim Taliban in Afghanistan.

"I think the Americans have embarked on a wrong course, and these lies are going to be disclosed sooner or later," Larijani said.

In neighbouring Iraq, he said, Iran has supported the democratic government, and does not relish the prospect of an influx of Iraqi refugees fleeing instability to join the "some 500,000" already in Iran.

Asked about charges by US military and intelligence sources that Iran is supplying Iraqi insurgents with sophisticated bombs that can pierce heavy armour, he said: "They are lying.

"Please present this information to us. For all the terrors that are happening in Iraq, is there any evidence that would show or dictate that we have been involved in it?"

On a more conciliatory note, Larijani said that Iran was willing to explore new contacts with the United States over Iraq after the two arch-foes held their first high-level direct talks in 27 years in late May.

"We are serious in this matter, and we do find it quite useful for the security of the region," he said. Asked about any Iranian preconditions to new talks, he said: "No, we are fully ready for negotiations in this matter."