The world's big powers have been told to expect a formal response as soon as today from the Tehran government that sets out an initiative designed to restart negotiations over Iran's nuclear programme. The letterfollows a conversation yesterday between Javier Solana, the European Union's foreign policy head, and Saeed Jalili, Iran's chief nuclear negotiator, that was described by Mr Solana's office as inconclusive. Further talks "were not ruled out", a spokesman said. Iranian state television said Mr Jalili "stressed the continuation of talks" and "contacts" in the phone call. The letter is expected to detail Iran's response to an initiative from the five permanent members of the United Nations Security Council plus Germany, known as "freeze-for-freeze", designed to find a way to start negotiations aimed at ending Iran's nuclear programme. After a meeting in Geneva on July 19, Iran had been given about two weeks to respond to the proposal. It would entail six weeks during which moves for UN sanctions would be halted in return for Iran capping the number of centrifuges used to enrich uranium. Negotiations proper would start once Iran suspended enrichment. Western governments fear the nuclear programme is designed to make a weapon but Iran insists it is for peaceful purposes. Western officials said Mr Jalili did not address yesterday the freeze-for-freeze proposal first made in June. If the offer were rejected, talks on a new round of sanctions would begin in September, they said. Gonzalo Gallegos, US state department spokesman, said the US and its allies were "disappointed" they had not yet received a response from Tehran. He said the US was committed to the "dual track" strategy. "We agreed, in the absence of a clear, positive response from Iran, we have no choice but to pursue further measures against Iran," he said. Meanwhile, European diplomats said the EU had agreed to implement new sanctions that go beyond those in the latest UN resolution designed to halt Iran's enrichment of uranium. These included increasing reporting requirements on Iranian financial institutions, in particular Bank Saderat; adding to the list of exports banned because they have a possible military use; and increasing advance reporting requirements of freight carriers Iran Air Cargo and Islamic Republic of Iran Shipping Line. Mohammad-Ali Jafari, commander of Iran'sRevolutionary Guard, warned it would be easy to shut the Strait of Hormuz, through which about 40 per cent of seaborne traded oil transits. This is the second time during the past two months that Mr Jafari threatened not to allow oil shipments through the waterway should Iran be attacked by the US or Israel. Copyright The Financial Times Limited 2008