Iran's ambassador on Monday warned France to back off its tough stance on Teheran's nuclear program - suggesting there could be economic consequences for French firms doing business in Iran if the Islamic Republic comes under new international sanctions. Ali Ahani, Iran's top envoy in Paris, said it would be "regrettable" if France continues its "very hard" line and its "alignment with the Americans" over Teheran's nuclear ambitions. Speaking to reporters at Iran's embassy, he said that if Iran faces new sanctions, Iranian leaders would be hard pressed trying to convince its citizens that French firms should be allowed to operate in Iran. Ahani did not specify which French companies he had in mind. French firms including automaker Renault and oil company Total have major business projects planned or under way in Iran. "We haven't decided anything on this issue," Ahani said, "but we hope that we will come to an understanding with the French government to choose a more reasonable, more just manner on this subject." Britain and France introduced a UN Security Council resolution Thursday to expand and toughen travel bans and the freezing of assets for more Iranian officials linked to the nuclear effort. Also Monday, a senior British diplomat said Iran may have continued work on nuclear weapons past 2003, the year US intelligence says such activities stopped. Simon Smith, the chief British delegate to the International Atomic Energy Agency, commented after an IAEA presentation of documentation that - if accurate - would strongly back US claims that Iran at one point worked on programs linked to attempts to make nuclear weapons. That assertion was also made by a US National Intelligence Estimate, summarized and made public late last year said. That report also said, however, that the Iranians froze such work in 2003. Asked whether the information presented to the IAEA's 35 board member nations indicated that Teheran continued such activities past that date, Smith said: "Certainly some of the dates ... went beyond 2003." He did not elaborate. Another diplomat at the presentation, who asked for anonymity because the IAEA meeting was closed, said some of the documentation focused on a 2004 Iranian report on alleged weapons activities. But she said it was unclear whether the project was being actively worked on then. A senior diplomat inside the meeting said that among the material shown was an Iranian video depicting mock-ups of a missile re-entry vehicle. He said IAEA Director General Oli Heinonen suggested the component - which brings missiles back from the stratosphere - was configured in a way that strongly suggests it was meant to carry a nuclear warhead. Smith and the senior diplomat both said the material shown to the board members came from a "multitude of sources," including information gathered by the agency and intelligence provided by the members themselves. IAEA, the UN nuclear monitor, released a report last week saying that suspicions about most past Iranian nuclear activities had eased or been laid to rest. But the report also noted that Iran had rejected documents that link it to missile and explosives experiments and other work connected to a possible nuclear weapons program, calling the information false and irrelevant. The report called weaponization "the one major ... unsolved issue relevant to the nature of Iran's nuclear program." Most of the material shown to Iran by the IAEA on alleged attempts to make nuclear arms came from Washington, though some was provided by US allies, diplomats told the AP. The agency shared it with Teheran only after the nations gave their permission. Meanwhile, Iran's UN ambassador accused a group on the US terror blacklist of fabricating allegations that Iran tried to make nuclear weapons in the 1990s. Ambassador Mohammad Khazee insisted that Teheran has resolved all outstanding issues about its nuclear program and should not face any new UN sanctions. He indicated that the United States was getting unreliable intelligence from Iranian opposition groups. The government believes "baseless" information provided to the UN nuclear watchdog agency by the US just a few days before its latest report came from an Iranian exile group that helped Saddam Hussein during the war, he said. "I'm afraid to say that, according to my information, some of these allegations were produced or fabricated by a terrorist group, which are listed as a terrorist group in the United States and somewhere else in Europe," Khazee said in an interview with The Associated Press. He appeared to be referring to the The Mujahedeen Khalq, also known as the People's Mujahedeen Organization of Iran, who were deemed foreign terrorist organizations by the US State Department in 1997. Last June, the European Union decided to keep the Paris-based opposition group on its terror blacklist.