Ahead of another round of talks between the P5+1 group of world powers and the Iranians next week in Lausanne, American negotiators have been seeking to both reduce expectations and lower opposition to an eventual nuclear agreement.

Following Israeli officials' complaints that they are not being updated on the talks, a flurry of meetings and phone conversations took place between senior US diplomats and the heads of Israel's National Security Council on the outline of the upcoming deal.

In a bid also to influence public opinion, Israeli journalists were briefed and told by a senior official that the US was "not in a rush" to sign the deal. They were also told that contrary to what has been leaked, the restrictions and increased monitoring of Iran's nuclear programme will not end after 10 years but "continue indefinitely".

Secretary of State John Kerry will join the talks on Sunday, along with his Iranian counterpart Mohammed Jawad Zarif. The pair have been engaged in a round of meetings in recent days, including with the leaders of Saudi Arabia. The Saudis, like Israel, are opposed to a deal which they see as a green light for Iran to become a "threshold nuclear state". Mr Kerry also travelled to Europe where he met foreign ministers from the UK, France and Germany.

There are widely divergent assessments coming from European diplomats on the chances of an agreement in the coming weeks, with some saying that "a deal is very close". Others are of the opinion that the gaps between the sides - particularly on the time limits for increased inspections of the nuclear programme and the timetable for the removal of sanctions - are too wide for an agreement to be reached by the end of the month.

Anti-deal

64 Senators back fresh sanctions
47 GOP Senators sent a letter to Iran's leaders warning that the next US president can cancel a deal

Efforts to derail the deal in Washington are ongoing, with a motion for new sanctions on Iran so far receiving the support of 64 senators, three short of a veto-proof majority.

Meanwhile, 47 Republican senators have signed a letter to Iran's leadership emphasising that while the Obama administration may sign an agreement, without congressional approval it would be "a mere executive agreement", which the president who replaces Barack Obama in 22 months could revoke "with the stroke of a pen".

The letters are designed to increase suspicion and boost the opposition to the deal that already exists in some circles in Iran. President Hassan Rouhani has been energetically lobbying influential clerics to get their support for an agreement. Some senior religious figures oppose the deal, which they see as a capitulation to the West and a betrayal of Iran's Islamic revolution.