"Dialogue must be without preconditions, because any precondition limits the framework of the dialogue and does not allow results to be achieved," foreign ministry spokesman Hamid Reza Asefi told reporters.

"The Islamic republic of Iran will not give up its rights. One cannot fix preconditions to hold negotiations without taking into account the position of the other party," he added.

A suspension of enrichment is a non-negotiable precondition in a proposal from the five permanent Security Council members -- Britain, China, France, Russia and the United States -- plus Germany.

The offer, presented to Iran on June 6, involves incentives and multilateral talks if Iran agrees to a temporarily halt the sensitive nuclear activity and cooperate with the International Atomic Energy Agency (IAEA).

Washington and its allies believe the Iranian programme is a cover for an attempt to build a nuclear weapon. Iran insists it is peaceful, arguing that it only wants to enrich uranium to make civilian reactor fuel and not the core of a nuclear weapon.

"If the European act with logic and reason, the chances for a result are there. If the Europeans respect our rights, they will have greater credibility. It is about logic, and not dignity," Asefi said.

He did not explicitly mention enrichment, but Iranian officials invariably refer to the activity as a "right" enshrined by the nuclear Non-Proliferation Treaty (NPT).

Iranian Foreign Minister Manouchehr Mottaki also refused to explicitly say if Iran would agree or refuse to suspend enrichment.

"We have started to seriously examine the offer," he told reporters. "After examining it, we will give our response."

Western officials say they expect a response from Iran before the end of June.

Chinese Prime Minister Wen Jiabao meanwhile put fresh weight behind the offer.

"We believe the Iran nuclear issue needs to be resolved through diplomatic channels," Wen told reporters after meeting Egyptian President Hosni Mubarak in Cairo.

"We also believe that the six countries involved have already put on the table a quite good proposal on a solution to the Iranian nuclear issue (which) has certainly laid a foundation for peaceful talks," said Wen, whose remarks were translated from Mandarin into English.

His comments came two days after a meeting between Chinese leader Hu Jintao and Iranian President Mahmoud Ahmadinejad, who also met Russian President Vladimir Putin a day earlier.

Washington had expressed fears that Iran would seek to test the unity of the major brokers in the nuclear crisis during the talks with Beijing and Moscow, which have traditionally taken a softer stance towards the Islamic republic and have so far opposed the use of sanctions.

"We believe that Iran is entitled to the right to a peaceful use of nuclear energy. At the same time Iran also needs to honour its due obligations and commitments," Wen said.

"The parties need to seize this opportunity and display even greater flexibility so as to resume the peace talks at an early date," he added.

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