The US and other world powers will next month meet Tehran’s chief nuclear negotiator to test the seriousness of Iran’s proposal for talks and gauge its willingness to discuss its uranium enrichment programme.

The meeting will be the first time the US has engaged directly in talks with Iran since Barack Obama came to office.

The administration has kept up its offer of unconditional engagement in spite of the turmoil over the June 12 presidential election, which Iran’s opposition says was massively rigged in favour of President Mahmoud Ahmadi-Nejad.

The election crisis exposed deep rifts within the Islamic regime, and has led to an overwhelming crackdown against the reformist opposition.

Javier Solana, European Union foreign policy chief, and Iranian chief nuclear negotiator Saeed Jalili on Monday agreed to hold the meeting on October 1. The encounter, at an as yet undisclosed venue in Europe, will involve senior diplomats from the US, UK, France, Germany, Russia and China.

Last week, Iran delivered a five-page proposal that ignored the controversial nuclear programme that world powers are seeking to curb but offered instead talks on a range of global problems, including the world financial crisis and reform of the United Nations.

The US, however, said it would put the nuclear issue on the table, even if Iran did not address it in its proposal.

Iran insists that the nuclear file is “closed” and not subject to negotiations. But in what could be an opening for a nuclear discussion, Hassan Qashqavi, the foreign ministry spokesman, on Monday said Tehran’s recent proposal addresses the removal of global concerns, including nuclear disarmament.

William Burns, the political director at the US state department, will attend the meeting, the first between Iran and the international community on its uranium enrichment plans since July 2008.

Western diplomats said late on Monday that although the US presence at the session would be an important signal of Washington’s willingness to talk to Iran, expectations of a breakthrough are low.

The US and its European Union allies have warned Iran that it must immediately begin negotiations over its nuclear programme if it is to avoid imposition of a fresh round of economic sanctions this year.

Some European diplomats suspect Iran’s offer of talks on October 1 is a tactical move, aimed at wrecking talks by the E3 plus 3 (the permanent members of the UN Security Council, plus Germany) on Iran at the United Nations next week, and delaying new sanctions.

“Foreign ministers of the E3 plus 3 are due to meet in New York next week to discuss what kind of warning to send to Iran,” said a diplomat from an EU state. “It’s now harder to get momentum for that if Iran says it will hold some kind of meeting the following week.”

Another EU diplomat said: “It’s important to meet, to try and probe where Iran stands. But all the mood music suggests a breakthrough is unlikely.”

US and European governments have also been under pressure from Russia, which has made clear it was reluctant to endorse new sanctions against Iran.