Iran and the representative of six world powers talked by telephone today over Tehran's disputed nuclear program but the Islamic Republic said it would press ahead despite a demand to halt the work.
Western officials had set an informal deadline of last Saturday for Tehran to respond to an offer by the powers to refrain from imposing more UN sanctions on Iran if it froze expansion of its nuclear work.
Shortly before the call between Iran's chief nuclear negotiator Saeed Jalili and European Union foreign policy chief Javier Solana, an Iranian official said Iran would not discuss the freeze idea. "The freeze-for-freeze issue will not be discussed," he said.
The West fears the program is aimed at building nuclear weapons.
The United States said after Iran missed Saturday's deadline that the UN Security Council had no choice but to expand sanctions. Iran says it was never given any ultimatum.
In comments likely to stoke tension, Iran's Revolutionary Guards chief said the Islamic Republic had the ability to close the Strait of Hormuz, a vital oil shipping route, if attacked. The Guards said they had tested a new naval weapon.
Washington has not ruled out military action if diplomacy fails to end the row. Worries about a conflict flaring up have rattled oil markets in the past.
"Mr Solana will be in touch with the authorities of China, France, Germany, Russia, the United Kingdom and the United States," an EU official said after confirming the phone talks.
Iranian state radio said: "They emphasized continuing the course of the Geneva talks. The preservation of this course requires a constructive and positive environment".
The two sides would consult again in coming days. it said.