A senior Iranian official warned Saturday that further UN sanctions over Teheran's contentious nuclear program could derail ongoing negotiations toward a settlement. Ali Larijani, Iran's top nuclear envoy, said after his latest round talks with European Union foreign policy chief Javier Solana that the international community should seek to keep negotiations alive, and chided nations that sought to punish the Islamic republic. It would be natural for some to try to destroy the negotiation process, Larijani told a news conference, referring to the prospect of new UN Security Council sanctions. However, "for (most) countries, the prevalence of tranquility would be more important," he said through an interpreter at a news conference after the talks in Lisbon, Portugal. Solana described the talks as "constructive," and said the two planned to meet again in three weeks. Since December, the council has imposed two sets of sanctions for Iran's refusal to freeze both its uranium enrichment and construction of a heavy-water reactor for producing plutonium. It also demands that Iran end its stonewalling of the International Atomic Energy Agency, or IAEA. On Friday, the IAEA said Iran had agreed to provide answers on past suspicious nuclear activities within two months - a sign that Teheran was ready to make concessions in order to weaken international pressure against it. But Larijani - speaking after meeting IAEA chief Mohamed ElBaradei at the agency's Vienna headquarters on Friday - suggested the offer was conditional on reaching a "political understanding with Mr. Solana" on Saturday. That was apparent shorthand for a larger deal that would allow for the start of talks between Iran and the five permanent council members and Germany, without the present precondition of a total enrichment freeze. Larijani reiterated in Lisbon that he intended to address outstanding issues with the IAEA, but provided no details in his brief comments. Both enriched uranium and plutonium can be used for the fissile core of nuclear warheads, though Iran insists its nuclear program is solely for the peaceful purpose of producing energy. While the key issue remains enrichment, any move by Teheran to share sensitive information with the IAEA could increase good will and feed sentiment for a compromise that might allow it to retain some elements of its enrichment program. In a further sign that compromise might be possible, British, French and German officials have begun debating whether to tolerate a less-than-full enrichment freeze by Iran - a stance that could put them at odds with Washington, officials in Vienna told The Associated Press on Friday. Germany was supportive of such a concession, while France was opposed and Britain noncommittal, said the officials, who included US and European diplomats and government employees. They said the talks were preliminary, however, and that nothing had been decided. Last month, officials told the AP that Iran last year considered stopping some - but not all - of its enriched-uranium producing centrifuge machines in exchange for a start to negotiations. But insistence from the US, Britain and France that Teheran fully suspend its program doomed chances of agreement. Larijani also told Solana last month Iran was willing to stop stonewalling IAEA investigations and provide full disclosure of its nuclear activities. But Teheran has yet to deliver - and similar promises in the past also were not followed up on. Multilateral talks with Iran broke off two years ago, after Teheran snubbed an offer of political and economic incentives in exchange for a long-term suspension of its atomic program. It then resumed enrichment. Iran's ultimate stated goal is running 54,000 centrifuges to churn out enriched uranium.