Iran on Wednesday made a formal request for a date and venue to be fixed for talks to resume with world powers focusing on Tehran\'s controversial nuclear programme. Iran\'s chief nuclear negotiator Saeed Jalili sent a letter to EU foreign affairs chief Catherine Ashton saying he wanted to see \"representatives from both sides in contact to set a date and place for the new round of talks,\" the official IRNA news agency reported. Ashton represents the so-called P5+1 group of world powers, comprising the United States, Russia, China, France, Britain and Germany. Last week, Ashton declared that the group was ready \"to resume talks with Iran on the nuclear issue,\" following an inital proposal she made in October last year that was accepted by Iran on February 14. In his latest letter, Jalili hailed that readiness and insisted on \"the need to have constructive, serious talks without preconditions and with the goal of having long-term cooperation,\" according to the Farsi-language report by IRNA. He also welcomed what he said was Ashton\'s position \"respecting the rights of the Islamic Republic of Iran to use nuclear energy for peaceful ends consistent with the Nuclear non-Proliferation Treaty.\" The last round of talks between Iran and the P5+1 broke down in Istanbul in January 2011. Western diplomats said the collapse resulted from Iran\'s insistence on discussing matters other than its nuclear programme. Tehran has repeatedly said its nuclear activities are exclusively peaceful. Western nations, though, believe they mask a drive to develop a nuclear weapons capability -- a suspicion crystallised in a report by the International Atomic Energy Agency last November that stopped just short, however, of stating proof of atomic bomb research existed. Sanctions by the United States and Europe hitting Iran\'s vital oil exports and its financial sector have dramatically ramped up in the past five months. Israel and the United States have also threatened possible air strikes against Iran\'s nuclear facilities, though Washington has said it is currently putting all its energy into diplomacy and the sanctions. A Russian newspaper, Kommersant, on Wednesday reported that Russia\'s foreign ministry had received a warning from US Secretary of State Hillary Clinton that the Iran-P5+1 talks were a \"last chance\" to resolve the crisis. \"She asked her Russian colleague to make this clear to the Iranian authorities,\" as Washington has no diplomatic relations with the Islamic Republic, the newspaper said. Iran has said it favours Istanbul again as the venue for the next round of talks.