But comments by a top Iranian official on the country's nuclear drive were less well received, the official said on condition of anonymity.

"The Iranians showed themselves to be very engaged, very interested, the tone was very good," she told AFP. "What was important for these two days was the tone, not the substance."

The discussions with a 12-person Iranian delegation headed by a senior foreign ministry official took place here on Wednesday for trade and economic aspects, and covered political questions on Thursday.

They were the first in 18 months after the EU had suspended the dialogue because of concerns over Iran's nuclear ambitions.

The resumption followed the confirmation of Iran's suspension of its uranium enrichment and reprocessing activities by the UN's nuclear watchdog, the International Atomic Energy Agency.

But tension remains, notably because Tehran has agreed to maintain the suspension of its uranium enrichment activities only as long as the talks on an EU trade accord continue.

"Suspension of enrichment is for a limited period to win the confidence of the international community," Iran's top nuclear negotiator Hasan Rowhani said Wednesday.

The EU official said: "The best is that we do not have these kinds of declaration during the negotiations.

"Declarations which do not conform to the letter and the spirit of the mid-November accord will not be well received."

The EU-Iran talks on a potentially lucrative trade pact were revived after a deal clinched in November by the European bloc's three most powerful members -- Britain, France and Germany -- for Iran to suspend uranium enrichment.

Iran's top negotiator with the EU, Ebrahim Rahimpour, has described this week's talks in Brussels as "positive".

"Both sides are interested to continue the work that we have started," he told the official Iranian news agency IRNA Thursday.

"Negotiations will continue in a more positive atmosphere which now prevails for closer political and economic cooperation," he was quoted as saying.

The EU underlined that the trade talks, which are expected to involve negotiating sessions roughly every two months, are aimed at agreeing a "first-generation" trade accord with Iran.

This would not give Iran any preferential access to EU markets, but would confirm its trade relations on the basis of those applying to all other World Trade Organization members, EU officials said.

The Iran-EU trade talks, which were launched in December 2002, were suspended in mid-2003 amid mounting tensions, particularly over Tehran's refusal to allow snap inspections of its nuclear facilities.

Wednesday's resumption of the trade talks was followed Thursday by the resumption of political talks on key concerns: human rights, regional security, terrorism and proliferation of weapons of mass destruction.

EU officials have made it clear that, while there is no direct link between the two sets of talks, problems in key areas of concern could lead to a new suspension of dialogue.