Details have emerged of how talks with Tehran in Geneva broke up at 11th hour after France and US took a robust stance

A meeting in a Geneva hotel room between the US secretary of state and his French counterpart led to an 11th-hour toughening of the west's position on Iran's nuclear programme that proved unacceptable to Iranian negotiators, say western officials.

John Kerry's Saturday-night meeting with Laurent Fabius was a late turning point in three days of intense talks among foreign ministers that resulted only in a decision to resume negotiations at a lower level in Geneva next week.

In the discussion in the US secretary of state's room at the Geneva InterContinental, Fabius insisted on two key points in the drafting of an interim agreement with Iran: there should be no guarantees in the preamble about the country's right to enrich uranium; and work would have to stop on a heavy-water nuclear reactor. Iran is building the Arak reactor, capable of producing plutonium, about 130 miles south-west of Tehran.

In the words of one French official: "Kerry was confident enough to accept what Fabius had to say." The two points were included in a three-page draft proposal put together by the EU foreign policy chief, Lady Ashton, who acts as a convenor for a six-nation group involved in the talks.

The draft agreement also imposed limits on Iran's enrichment capacity and its stockpiles of enriched uranium in return for limited sanction relief.

At 9.20pm on Saturday the agreement was put before foreign ministers from the UK, Germany, Russia and the deputy foreign minister of China, who make up the rest of the "P5+1" group, which has been negotiating with Iran for seven years.

"Kerry was even more forceful in presenting this draft than Fabius. He got behind it," the French official said. The P5+1 ministers approved it, and at 10.50pm it was put to the Iranian foreign minister, Mohammad Javad Zarif, who had joined the meeting in a conference room in the hotel.

However, in the preamble of a joint statement, Zarif had been seeking language that would at least implicitly recognise Iran's right to enrich uranium. He had also insisted on construction continuing at Arak, and suggested that international concerns could be assuaged if the work stopped short of putting uranium fuel in the reactor and turning it on.

But at 10 minutes past midnight on Sunday morning, it was agreed that all parties would consult their capitals and try again at a meeting of foreign ministry political directors on 20 November. Ministers would not attend but could be on hand if needed.

Arriving in Abu Dhabi after the meeting, Kerry singled out Iran for the failure to agree. "The French signed off on it; we signed off on it," he said. "There was unity, but Iran couldn't take it."

Zarif took to Twitter to rebut that claim. "Mr Secretary, was it Iran that gutted over half of US draft Thursday night? And publicly commented against it Friday morning?" Zarif said in a pointed reference to Fabius's role. "No amount of spinning can change what happened in 5+1 in Geneva from 6PM Thurs. to 5.45 PM Sat. But it can further erode confidence"

Western officials conceded that unity had been achieved only on the last night of the negotiations, leaving little time for the Iranians to respond; much of the preceding 60 hours of talks had been among the P5+1 group seeking a common position.

The foreign secretary, William Hague, who took part in the talks, said that although there were still gaps between the sides, it should possible to resolve them. "While I cannot go into the details of the discussions while the talks continue, I can say that most of those gaps are now narrow, and many others were bridged altogether during the negotiations."

The UK today on Monday named a new non-resident chargé d'affaires for its embassy in Tehran, which has been empty since it was stormed by a mob in 2011. The appointment of Ajay Sharma, the current head of the Iran desk, followed bilateral talks on the margins of the Geneva talks. He is due to visit Tehran later this month, the first time a British diplomat has been there for two years.

Western officials argued strongly that the talks had made unprecedented progress on a previously intractable issue. "No breakthrough yet, but definitely no failure," said a senior diplomat. "The collective assessment of the group was that some more time would still be needed. That was not just the assessment of the French."

Another western diplomat added: "This issue was far too technical and too complicated for it to have been solved in a couple of days." But he added the sudden, unplanned convergence of foreign ministers on Geneva on Friday had created unrealistic expectations.

Kerry, prompted by an Iranian leak on Thursday night that he was on the way, asked to attend the negotiations. When he was then invited by Ashton, the other foreign ministers rushed to join him.

Fabius arrived first, concerned that the US and Iran would strike a bilateral agreement and present it to the other attendees as a fait accompli. But he immediately angered his colleagues by breaking a long-established agreement not to discuss the substance of the talks in public when he voiced his reservations on French radio.

Fabius denied that he had acted as a spoiler at the talks. "France is neither isolated, nor does she blindly follow," he told Europe 1 radio. "We are firm but not closed-minded, and I have great hope that there will be a good agreement."

Mark Hibbs, a nuclear expert at the Carnegie Endowment for International Peace, agreed that France had been unfairly lambasted. "At the end of the day, when cooler heads prevail, the French intervention will be seen as constructive," he said. "Only if you stop work on Arak can you decompress the discussions that there will have to be over the next few months."

It has also become clear that France was not the only participant in Geneva seeking to reflect the concerns of Iran's neighbours. Ashton believes any breakthrough would need to be "sustainable". She has expressed fears that an agreement that fails to pass muster with Israel, Saudi Arabia and others in the region could trigger a nuclear arms race in the Middle East.

While the Geneva talks failed to produce an agreement, the head of the International Atomic Energy Agency (IAEA), Yukiya Amano, secured a deal in Tehran yesterday/today giving his inspectors access to two sites: a plant producing heavy water for the Arak reactor, and a uranium mine in Gchine on the Gulf coast.

The agreement was significant as it involved Iran going beyond the letter of its agreement with the IAEA in offering transparency, and an annex also obliged Tehran to provide design information on Arak and any other new reactors and uranium enrichment plants Iran might be planning. But it does not address the critical issue that has deadlocked the IAEA and Iran for years – the agency's investigation into any nuclear weapons development work Iran might have conducted in the past.

"I wouldn't say this agreement was entirely ho-hum but it does not address the big ticket issues. They aren't mentioned," Hibbs said. "It also talks about 'managed access' to the sites, so everything is still subject to further agreement by Tehran, and that makes it hostage to the atmosphere of the broader negotiations."