A top American official says he doesn't expect any breakthroughs during a key meeting with major world powers on Iran's nuclear program, but urged China and Russia to agree to sanctions.

"I wouldn't say it's going to be a breakthrough meeting but I do think it is an important meeting along the way. It's high time that we passed a [United Nations] Security Council resolution on Iran," U.S. undersecretary of State Nicholas Burns told reporters in France.

Burns will join officials from Britain, France, China, Russia, and Germany later in Paris for a meeting of the Organization for Security and Co-operation in Europe.

The group will discuss possible sanctions against Iran, which rejected a UN Security Council deadline to end uranium enrichment by Aug. 31.

Burns urged Russia and China to join the other permanent members of the Security Council in reaching an agreement on sanctions.

"We've waited long enough. We've had hours and hours of discussions and we really do need the Russian and Chinese governments to shift into third or fourth gear … and to work more quickly to agree with us on the basis of a resolution."

"We know it's going to impinge upon Iran's nuclear and missile programmes. We know that we all want to cut off the ability of Iran to seek financial support, or technological support to continue its enrichment or missile programmes, or heavy water reactor programmes," he said.

France's foreign minister on Monday said agreement on a Security Council resolution was near.

Iran warns Europeans

Earlier Tuesday, Iranian President Mahmoud Ahmadinejad warned European countries that co-operating with the U.S. on sanctions would be "an act of hostility."

"I'm telling you in plain language that as of now on, if you try, whether in your propaganda or at international organizations, to take steps against the rights of the Iranian nation, the Iranian nation will consider it an act of hostility," Ahmadinejad said in a speech before thousands of people in northern Iran.

"And if you insist on pursuing this path," he continued, Iran "will reconsider its relations with you."

It was the first time that Ahmadinejad had threatened to downgrade relations with European nations, which are responsible for a large portion of Iran's international trade.

Ahmadinejad doesn't have the final say in the country's policy, however.

That falls to supreme leader Ayatollah Ali Khamenei.

Washington and other Western countries believe Tehran is secretly trying to build a nuclear weapon. Iran maintains its nuclear program is for peaceful purposes, such as finding new forms of energy.

With files from the Associated Press