Iran postponed crucial nuclear talks with the European Union on Wednesday in apparent anger at an exiled opposition leader's visit to the European Parliament, but the meeting will go ahead on Thursday.
EU foreign policy chief Javier Solana, who last month put to Tehran a package of incentives offered by major powers for it to give up uranium enrichment, voiced surprise and impatience after a phone call with the chief Iranian nuclear negotiator.
"I was surprised to hear that Ali Larijani ... has decided at the last minute to postpone his trip to Brussels as previously agreed with him to take place today," Solana said in a statement.
"I have made clear to the Iranians and to Dr Larijani that we want to proceed rapidly to examine the ideas I put to him early last month."
Solana said he would meet Larijani in Brussels on Thursday and again on July 11, keeping up Western pressure for a clear answer before leaders of the Group of Eight industrial powers meet in St Petersburg on July 15.
Iran, suspected by Western officials of playing for time and trying to divide the international community, has said it will give its response by August 22.
Iranian Foreign Minister Manouchehr Mottaki confirmed in Tehran that Wednesday's talks were off but gave no reason.
But an EU diplomat said the Iranians had cited a visit to the European Parliament in Strasbourg on the same day by the leader of the National Council of Resistance of Iran, described by Tehran as a terrorist group.
Asked whether the visit by Maryam Rajavi was the reason for the sudden postponement, an Iranian official told Reuters: "It could have had a negative impact on the meeting."
Rajavi, who is based in France and whose organisation is the political wing of the outlawed People's Mujahideen armed group, was invited to the legislature by a cross-party group of EU lawmakers who call themselves "Friends of a Free Iran".
Rajavi held a news conference at the EU legislature in the eastern French city but cancelled plans to meet parliamentary groups in what she said was an attempt to avoid giving the Iranian authorities an excuse to stop the nuclear talks.
"I wish to remove any pretext that the mullahs might have and I wish to make negotiations possible for the international community, and that is why I have asked that the meetings be deferred," she told journalists.
Rajavi's group was the first to publish details of Iran's clandestine nuclear enrichment programme in 2002.
Diplomats said divisions in the UN Security Council over what action to take on Iran meant there had been little chance of Tehran responding either at the Brussels meetings or before the G8 summit in Russia.
The United States has accused Iran of having a secret programme to build nuclear weapons. Iran denies the charge, saying its nuclear programme is solely for power generation.
Iran says it sees ambiguities in the June 6 offer by Germany and the five permanent, veto-wielding UN Security Council members -- the United States, Britain, France, Russia and China.
The major powers offered a state-of-the-art nuclear reactor with a guaranteed fuel supply, economic benefits and support for the idea of a regional security framework if Iran halted uranium enrichment.
Diplomats say that as Russia and China are unlikely to back any UN sanctions against Iran at this stage, the West is in no position to set deadlines.