"If suspending uranium enrichment is a prior condition for negotiations, it is impossible to respond positively to this," Deputy Foreign Minister Mehdi Mostafavi said in remarks reported by the ISNA student news agency.

The international community has demanded that Iran suspend enrichment, which it fears could be used to make nuclear weapons. Tehran rejects the demand, insisting its nuclear programme is for peaceful energy purposes.

On Saturday the Security Council unanimously approved further sanctions against Iran for persistently refusing to stop enriching uranium.

The resolution, agreed after days of behind-the-scenes bargaining, blocks all Iranian arms exports and freezes the overseas assets of 28 additional officials and institutions linked to Iran's nuclear and ballistic missile programmes.

It also restricts financial aid or loans to Tehran, and sets a fresh 60-day deadline for Iran to comply with UN demands or face "further appropriate measures."

"We are continuing our peaceful nuclear activities under the terms of the Non-Proliferation Treaty and the International Atomic Energy Agency, and in this context we are ready for talks with the agency and Security Council members," Mostafavi said. After the resolution was approved, the five permanent members of the Security Council -- Britain, China, France, Russia and the United States -- plus Germany issued a statement saying the crisis should be solved through negotiations.

European Union foreign policy chief Javier Solana was then tasked with contacting Iran's lead nuclear negotiator, Ali Larijani, to discuss how such talks might resume.

A top European envoy on Monday renewed an offer from six world powers to talk with Tehran over its nuclear ambitions, and a senior Iranian negotiator agreed to stay in contact in an effort to find common ground.

European Union foreign policy chief Javier Solana's telephone conversation with Ali Larijani, Tehran's top nuclear negotiator, was the first exchange between the representatives of Iran and the international community since the UN Security Council toughened its anti-Iran sanctions because of the Islamic republic's refusal to freeze uranium enrichment.

Solana spokeswoman Cristina Gallach emphasised it was not a negotiating session but more a message to the Iranian side that the international community was interested in "renewing ... talks and solving in a negotiated matter" differences separating the sides.