Influential cleric urges Iran's leaders to reject nuclear deal

Ayatollah Ahmad Jannati said in his Friday sermon: "The package they have presented is a package [that is] good for them. It's not good for Iran."

It was not immediately clear whether his statement in any way represented the views of the Iranian government, but he is the head of the powerful Guardian Council, a constitutional watchdog, and his comments reflect conservative pressure on ministers to reject the proposals.

Ayatollah Jannati spoke out as George Bush, the US president, said Iran had "weeks not months" to respond to the offer, and Jacques Chirac, the French president, said the international community "cannot accept" an Iranian effort to build a nuclear weapon.

Javier Solana, the European Union's foreign policy chief, presented the package to Iran on Tuesday.

Its contents have not been made public, but diplomats said it included economic rewards and a provision for some US nuclear technology if Iran stopped enriching uranium. Crucially, the five permanent members of the United Nations Security Council plus Germany are demanding only that Iran suspends enrichment, not permanently halts it. The offer, however, also contains the implicit threat of UN sanctions if Iran remains defiant.

Iran's initial reaction to the package was relatively upbeat. But Tehran has said it will announce its position only after carefully studying the package. Mr Solana said he expects a reply within "weeks".

Mr Jannati insisted Iran must continue enriching uranium. "We have to maintain enrichment to the level of 3.5 to 5 per cent. They have no choice but to accept it," he said. Uranium enriched to this level is used in nuclear reactors to produce electricity. It needs to be enriched to more than 90 per cent for use in a warhead.

Iran is under intense international pressure to accept the deal. Ali Larijani, the country's top nuclear negotiator, has said that the proposals have "positive steps" but that talks were needed to clear up ambiguities. Iran promised to study the proposals seriously, but gave no timeframe for a response.

In a major policy shift, the United States agreed last week to join Britain, France and Germany in talks with Iran, provided Tehran suspends all suspect nuclear activities. Iran's government has welcomed the idea of direct talks with Washington but rejected any preconditions.

Mahmoud Ahmadinejad, the Iranian president, who portrays his country as having forced Washington and its allies to accept the Islamic regime's position, has sent out mixed signals on how much is open for negotiation.

Mr Bush said that if Iran did not respond to the offer and suspend enrichment,

"there must be a consequence" and that it would be action taken in the UN Security Council.

"We have given the Iranians a limited period of time, weeks not months," he said.

Mr Chirac stressed that Iran would not be allowed to develop nuclear weapons technology. "We cannot accept that it has launched and pursued a process that could, notably through enrichment ... lead to the creation of a nuclear weapon," he said.

Austria, which holds the EU presidency, said Iran had until next month's G8 summit to consider the incentives package.