NEW YORK -- In a setback for the United States, Iran won a two-month reprieve from new United Nations sanctions over its nuclear program. Washington and its European allies ceded to Russian and Chinese demands to give Tehran more time to address international concerns.

An agreement reached Friday in talks among six key nations and supported by the European Union gives Iran until November to make progress in answering questions about the program that many have alleged is a cover for nuclear weapons development.

The decision marks another blow for Washington in its diplomatic struggle to toughen existing UN sanctions on Iran, whose leader this week declared to the UN General Assembly that the nuclear issue was "closed" and vowed to defy attempts to add new penalties.

Despite increasing support for new sanctions in Europe -- particularly from Britain, France and Germany -- Russia and China refused to yield, insisting on giving Tehran more time to accept an offer for negotiations in exchange for suspending its nuclear activities.

Foreign Minister Sergei Lavrov cautioned that Friday's agreement did not automatically mean new sanctions in November.

"The statement is very unambiguous," he told reporters at the UN. "What we discussed today is to concentrate on doing everything to help negotiations to succeed."