Six world powers failed to reach an accord despite "substantive progress" on a UN resolution to punish Iran for its nuclear activities, the French Foreign Ministry said after closed-door talks in Paris on Tuesday. The five permanent UN Security Council members plus Germany remained split over key questions of visa bans and asset freezes for Iranians linked to nuclear development, which Russia is resisting, a top European diplomat said. After months of diplomatic wrangling, the United States and France had expressed hope that Tuesday's talks would produce a resolution imposing sanctions on Iran for defying UN demands to stop uranium enrichment. The process can produce material for atomic warheads as well as electricity. "We made substantive progress on the scope of the sanctions targeting proliferation-sensitive activities. There remain several outstanding issues, upon which we will reflect over the coming days," the French Foreign Ministry said in a statement late Tuesday night. "We are now close to a conclusion of this process." The discussions now move to the UN in New York. The Americans and Europeans are pushing for a resolution by the end of the year. Iran, meanwhile, issued new threats of retaliation in case of sanctions. Iranian President Mahmoud Ahmadinejad vowed Tuesday to stick by the nuclear program and issuing a new threat to downgrade relations with the 25-nation EU if European negotiators opted for tough UN sanctions. The EU is Iran's biggest trading partner. "We are coming up to the time (when) the credibility of the UN is at stake," US State Department spokesman Sean McCormack said in Washington before the Paris talks. Illustrating the divisions that have tangled the negotiations, Russian Foreign Minister Sergey Lavrov said earlier Tuesday that imposing wide-ranging sanctions would be irresponsible. "We believe that to impose these kind of sanctions would be ... disproportionate to the real situation. We will achieve the opposite results," Lavrov said in Brussels. "We believe this is wrong. We will work in a more responsible way." Still, a high-ranking European diplomat said the Russians made some concessions at Tuesday's talks. The Russians agreed to a measure prohibiting financial transfers to "problematic" Iranians linked to nuclear or ballistic programs, the diplomat said, on condition of anonymity because of the sensitivity of the talks. "We shouldn't be too pessimistic," he said. Russia still opposes the broader asset freeze that the European players - Britain, France and Germany - proposed in a draft UN resolution presented in October, the diplomat said. And the question of travel bans for those involved in Iran's nuclear and missile programs remains "blocked," he said. The Europeans and Americans support the bans and Russia opposes them. The Security Council has been at odds over how to deal with Iran's defiance of an Aug. 31 UN deadline to halt uranium enrichment. Western powers accuse Iran of seeking nuclear bombs, while Teheran insists it only wants nuclear energy. The Europeans and Americans want tough sanctions; Russia and China have pushed for dialogue, despite the failure of an EU effort to bring the Iranians to the negotiating table. Currently all are working off the European draft resolution, and Russia's suggested amendments to it. The resolution would order all countries to ban the supply of materials and technology that could contribute to Iran's nuclear and missile programs. Lavrov said Russia supported such measures. It also imposes a travel ban and asset freeze on people and companies involved in those programs - both measures Russia wants deleted. The Russians also remain resistant to a measure expanding the powers of the International Atomic Energy Agency to monitor Iran's nuclear program, considering that a "provocation" to Iran, the diplomat said. The draft resolution would exempt a nuclear power plant being built by the Russians at Bushehr in Iran, but not the nuclear fuel needed for the reactor. Russia wants to remove any mention of Bushehr. Washington's patience appears to be wearing thin. When asked earlier Tuesday when he expected Russia and China to join the others in supporting the resolution, the American participant in the discussions, Undersecretary of State Nicholas Burns, replied: "This afternoon would be a good time."