The US and Iran have rejected each other's opening offers over the Islamic regime's nuclear programme but European negotiators remain hopeful that a long process of bargaining lies ahead, rather than a rapid slide into a US bombing campaign.

Iran quickly dismissed concessions put forward by the Bush administration last week as worthless. US officials, in private, have been equally dismissive of a technically complicated Iranian offer that would allow it to preserve critical parts of its nuclear fuel cycle under an intrusive system of inspections.