The United States said it would study Iran's response carefully but added that it was ready to move ahead quickly in seeking UN enforcement action if Tehran did not suspend sensitive nuclear fuel cycle work as demanded by the Security Council.

Iran's nuclear negotiator Ali Larijani delivered Tehran's written response to representatives of the five permanent Security Council members plus Germany which drew up the package of incentives for Iran to renounce uranium enrichment and reprocessing activities.

"Iran is ready for serious talks with the 5+1 group from Aug. 23 over the offered package," the student news agency ISNA quoted Larijani as telling the envoys.

He did not elaborate on what was in the written response, and made no direct reference to Aug. 31 deadline for Iran to freeze enrichment or risk UN sanctions.

Earlier rejection?

But all the indications ahead of Iran's submission were that it was set to reject the basic precondition set by the six powers.

Ayatollah Ali Khamenei, who has the last word on all key policy issues, had said Monday that Iran was determined to press ahead with its nuclear program despite the Security Council deadline.

Atomic Energy Organization deputy head Mohammad Saeedi said the same day that Iran would "provide Europe with an exceptional chance for an understanding and a return to the negotiating table," but insisted an enrichment freeze was "no longer possible."

Different approaches

Divisions were emerging among world powers over how to handle the crisis, with the United States pushing for sanctions while China said punishing Iran was not the way to resolve the international concerns about the purpose of its nuclear program.

"We will obviously study the Iranian response carefully," US ambassador to the United Nations John Bolton told reporters in New York. "But we are also prepared, if it does not meet the terms set to proceed here in the Security Council ... with economic sanctions."

"I think we will be prepared to submit elements of a resolution in the council very quickly," he said.

Washington suspects Iran's nuclear program is a cover for an attempt to produce a bomb. But Iran, the world's fourth largest oil producer, insists it is purely for peaceful power generation.

The six powers' proposal, which was originally submitted to Tehran in June, offers trade and technology incentives in return for a freeze on enrichment, which can make the fuel for nuclear power stations or in extended form can produce the fissile core of an atom

bomb.

Israel in the crosshairs

In Israel, a cabinet minister and former Mossad spy said the country should learn the lessons of its offensive against Hezbollah militants in Lebanon and prepare for an Iranian attack.

One of Iran's top clerics warned last week that if the country is attacked by the United States and Israel, it would retaliate with ballistic missile strikes against Tel Aviv.

US President George W. Bush had said Washington would take the lead in demanding enforcement action if Iran failed to halt nuclear work. He has not ruled out a military option.

"There must be consequences if people thumb their nose at the United Nations Security Council," he said. "We will work with people on the Security Council to achieve that objective."

But a Chinese official said Beijing opposed sanctions.

"We have all along stood for a peaceful settlement of the issue through negotiations, rather than resorting to force or threatening sanctions," said Sun Bigan, special envoy to the Middle East. "Resorting to force and sanctions cannot fully solve the problems."