With a week to go before the next round of negotiations with Iran in Moscow, the mood music is discordant to say the least. Iran has taken accusing its six-nation group of negotiating partners of a lack of preparation and commitment to finding a solution. The EU, representing the six powers at the talks, responded by pointing out it had handed the Iranians a written proposal in Baghdad late last month and was waiting for a response.

At the end of last week, it appears confusion slipped into farce when the deputy Iranian negotiator, Ali Bagheri, claimed to his EU counterpart, Helga Schmid, that he was not aware of any such proposal, even though he was there at the table when it was handed over. Consequently, Schmid resent the text over the weekend.

The deal on offer is as follows: Iran stops production of 20%-enriched uranium, the biggest proliferation concern, and shuts down production altogether at the underground plant where some of it is being made. In return, Tehran would receive fabricated fuel plates for its medical research reactor, help with nuclear safety and much-needed spare plants for airlines.

The Iranians have not addressed the proposal either in public or in private. A western official at the last round of talks in Baghdad said the chief Iranian negotiator, Saeed Jalili. did not so much as glance on the document as it was handed over. Similarly, Bagheri did not mention it in his latest broadside against the EU and the six-nation group published today.

Bagheri's newly acerbic tone has taken European officials by surprise. In the run-up to Baghdad and at Baghdad itself, he came across as the 'good cop' in the Iranian team - urbane, polite and apparently flexible. It is possible he appeared too flexible. At one point in Baghdad Jalili gave Bagheri a dressing down in front of western diplomats in an apparent display of who was boss. Bagheri may be adopting a tougher public tone to ensure he is viewed as being on-message back in Tehran. As one western official put it: "What's Farsi for cover your ass?"

The foreign ministry political directors from the six-nation group (US, UK, France, Germany, China and Russia) are meeting in Strasbourg today and tomorrow to try to figure out how to keep the talks on track. The EU foreign policy chief, Catherine Ashton is due to talk to Jalili by phone tonight, and the Russian foreign minister, Sergei Lavrov, is to fly to Tehran on Wednesday to try to ensure that the Moscow round is not remembered as the dead-end of nuclear diplomacy.

From Washington, Laura Rozen, who follows the talks for Al Monitor, reported last week that the Obama administration was weighing up a possible change of tack, pushing for a comprehensive deal rather the piecemeal, confidence-building proposal put on the table in Baghdad.

European diplomats said they had heard mixed signals from the policy debate in Washington and would wait to see what the American chief negotiator, Wendy Sherman, brought to the table in Strasbourg. Their bottom line: this will ultimately be a deal between the US and Iran and we will back anything that has a chance of breaking the impasse.

By the way, the Farsi equivalent for 'cover your ass' is apparently: "Daste pish mijire, ke pas nayofteh", which means "you are stretching out your hand so as not to fall".