Iran and Russia on Tuesday ended two days of talks on a Kremlin offer to conduct uranium enrichment for Teheran, amid pessimism that the Islamic regime will accept what is widely seen as its last chance to stave off sanctions over suspicions it has a covert nuclear weapons program. An initial round of consultations between top national security officials from both countries on Monday made no visible progress, and on Tuesday experts from the Russian Foreign Ministry and atomic energy agency held discussions with the Iranian side. The delegation was to leave Moscow for Teheran later Tuesday. Russian Foreign Minister Sergey Lavrov declined to label the talks a failure. "I would be cautious about using the term 'failure' or 'setback' as long as the negotiations have not finished," he said in televised remarks. Russia's atomic chief, Sergei Kiriyenko, was set to visit Iran on Thursday for further talks. But a senior Russian lawmaker expressed frustration at the Iranian stance. "Unfortunately, Iran so far has not shown sufficient good will," said Konstantin Kosachev, head of the lower house of parliament's foreign affairs committee, as quoted by news agencies. Russia's offer has been backed by the United States and the European Union as the final opportunity to ease international concerns over Iran's nuclear program without seeking sanctions, but Iran has adamantly insisted on maintaining a domestic enrichment effort. The Kommersant daily reported Tuesday, citing an official in the Russian delegation, that the closed-door talks the previous day broke up after more than five hours without "any hope of reaching an agreement." The official spoke on condition of anonymity because of the sensitivity of the negotiations. Lavrov said after the meeting on Monday that Iran should resume the moratorium on uranium enrichment activity that is seen by the US and other Western nations as a cover-up for a suspected atomic weapons program. But the head of the Iranian delegation in Moscow, deputy secretary of the Supreme National Security Council Ali Hosseinitash, ahead of the Moscow talks said that Iran did not intend to renounce its right to produce nuclear fuel domestically. The Russian offer is widely seen as a final opportunity for Iran to address the West's concerns before a March 6 of the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), that could start a process leading to punishment by the UN Security Council. Under Moscow's plan, Iran's enrichment activities would take place on Russian soil to ensure no uranium is diverted for nuclear weapons. Enrichment is a process that can produce either fuel for a nuclear reactor or material for a warhead. Tensions escalated earlier this month when the IAEA reported Iran to the Security Council. Iran responded by suspending certain aspects of its co-operation with the IAEA - including allowing surprise inspections of its nuclear facilities - and confirmed that it had resumed small-scale uranium enrichment. Experts have said Iran would like its scientists to have access to the Russian enrichment facility and hope to retain the right to conduct some part of the enrichment process at home. Kiriyenko, the atomic energy chief, said Moscow was ready to "do everything possible to give [Iran] a chance to get out of this difficult situation in a peaceful, calm way," RIA-Novosti reported. But Kosachev voiced fears that Iran's defiance of the international community could land it in the same predicament as North Korea, which openly says it is pursuing a nuclear weapons program. "In this situation, we could start moving toward the North Korean scenario, with Iran isolating itself, leaving the [Nuclear] Nonproliferation Treaty and ending cooperation with the IAEA," Interfax quoted him as saying.