Ali Larijani, Iran's top nuclear envoy, said after his latest round of 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 said, referring to the prospect of new UN Security Council sanctions.

However, "for (most) countries, the prevalence of tranquillity 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.