"I think it's abundantly clear that Iran has no intention of meeting the deadline and meeting the condition that the countries put down three months ago," Undersecretary of State Nicholas Burns said.

"We believe the sanctions regime will be agreed to in September by the Security Council and we're going to work towards that with a great deal of energy and termination," he said on CNN.

"There has to be international answer and we believe there will be one," he said.

The Security Council has given Iran until Thursday to suspend all uranium enrichment and reprocessing activities, which Washington and its allies suspect are a cover for production of nuclear weapons.

Iran insists its nuclear program is for the civilian production of energy only and has repeatedly said it will not halt the program.

Burns, the State Department's third ranking diplomat, is expected to meet officials from the other permanent members of the Security Council -- Britain, China, France and Russia -- plus Germany early next week in Europe for the first "formal meeting" on sanctions, a department spokesman said.

Talks on specific language for the UN resolution imposing the sanctions will also be taking place in coming days UN headquarters in New York, said the spokesman, Sean McCormack.

Burns said he was confident that Russia and China -- the most reticent of the major UN powers to back punitive measures against Iran -- would agree to sanctions.

"The Iranians have not been able to separate us from the Europeans or from Russia and China," he said.

"I think this coalition will stick together. The Iranians will have to put that in calculations," he said.

The United States has provided few specifics of the sanctions it will seek if Iran fails to comply, other than to say it wants a progressive package of punitive measures to be phased in over time.

These are expected to begin with minor steps like travel bans on Iranian officials and a freeze on Iranian assets, but could escalate into a broader embargo on trade or foreign investment in Iran.

Burns brushed aside concerns that Iran, a major oil producer, could respond aggressively to sanctions, possibly by halting oil exports to some nations or by trying to hamper maritime traffic in the Gulf region.

"We're not going to be intimidated by anything they do," he said.

"The Iranians have to sit back and calculate the cost of isolation, the increased pressure that's going to come their way, and this is not going to be a pleasant time for them," he said.

Burns also warned Tehran against seeking to further destabilize the Middle East through its ties to radical Shiite movements in Iraq, Lebanon and the Palestinian territories.

"That would be profound miscalculation on the part of Iranian government," he said.

Speaking earlier, McCormack said the launch of moves towards sanctions did not close the door to a possible Iranian turnaround.

"It doesn't mean at any point along the line here, even while those discussions are ongoing, that Iran can't come to the P-5-plus-one and say, 'We are going to meet the conditions'" of the UN resolution," he said.

Iran announced earlier Wednesday that its top nuclear negotiator, Ali Larijani, would meet next week in Europe with EU foreign policy chief Javier Solana, creating another opportunity for Tehran to address the UN demands.

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