Iranian officials have in the past ruled out using oil as a weapon in Iran's nuclear standoff with the West, but Khamenei's comments suggested Iran could disrupt supplies if pushed.

His remarks, which are likely to unsettle wary oil markets, come days before EU foreign policy chief Javier Solana is due to deliver a package of incentives agreed by six world powers and designed to persuade Iran to abandon plans to make nuclear fuel.

"If you (the United States) make a wrong move regarding Iran, definitely the energy flow in this region will be seriously endangered," Khamenei, who has the last word in all matters of state, said in a speech, which discussed the dispute.

Washington accuses Tehran of seeking to develop atomic weapons under cover of a civilian nuclear power programme, a charge Tehran denies.

The United States says it wants a diplomatic solution but has refused to rule out military action.

Washington has offered to join European countries in talks with Iran about the nuclear program, but says Iran must first suspend uranium enrichment. Iran has so far rejected the demand, saying enrichment is a national right.

President Mahmoud Ahmadinejad said on Saturday Iran would consider the proposals from the United States, Russia, China, France, Germany and Britain but also insisted that the crux of the package was unacceptable.

The incentives being offered have not been publicly announced, but diplomats have been working on themes ranging from offering nuclear reactors to giving security guarantees.

A date for Solana's visit to Iran to deliver the package has yet to be announced. Iranian officials said the visit was expected in the next few days.

Khamenei did not explicitly refer to enrichment in his speech that marked the anniversary of the death of Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic.

But he said: "We are committed to our national interests and whoever threatens it will experience the sharpness of this nation's anger."

He also praised the efforts of the country's nuclear scientists in developing home-grown nuclear technology as a "brave move" and dismissed what he said was the West's campaign against the country's atomic programme.

"Today our nation has taken a step forward and has bravely resisted," he said. "There is no international consensus against Iran's nuclear program except by some ... monopolist countries and this consensus has no value."

Khamenei spoke from a podium emblazoned with Khomeini's words "America cannot do a damn thing." His speech listed what he said were US failures in Iraq, Afghanistan, the Palestinian territories and elsewhere in the area.