Along with France and Germany, British officials were drafting a resolution that would urge the International Atomic Energy Agency (IAEA) to act when it starts a week-long meeting today. It is likely that the so-called EU3 will only proceed with the proposed resolution if they are confident of obtaining a substantial majority.
The move follows a speech on Saturday evening at the UN headquarters in New York in which the Iranian President, Mahmoud Ahmadinejad, told the General Assembly that he would defend his country's "inalienable right" to produce nuclear energy. He also rejected a European offer of economic incentives if Iran halted its uranium enrichment programme, and said that his country was a victim of "nuclear apartheid".
Yesterday the Foreign Secretary, Jack Straw, said that Mr Ahmadinejad's comments had been "disappointing and unhelpful". He told the BBC: "It's all the more disappointing given the fact that [EU negotiators] have spent much of the last few days in discussions with Iran."
He added: "Successive Iranian ministers and presidents and, indeed, the spiritual religious leader Ayatollah Ali Khamenei, have said 'we have no nuclear weapons' and 'we have no intention of gaining nuclear weapons'. But what they are doing, and what has been disclosed and also what we think has not been disclosed fails to add up."
The West accuses Iran of covertly seeking to develop a nuclear arsenal. Led by the EU3, it has pressed Iran to freeze uranium enrichment activities and re-engage in negotiations.
Tensions have increased since Iran broke UN seals and resumed work at a uranium conversion plant at Isfahan last month. Work there had been suspended under a deal in November with the EU countries.
A British Government source told The Independent that Mr Straw was spending the day speaking with foreign ministers from the 35-member IAEA, while officials were working out the likely level of support for a resolution to report Iran and put pressure on it to restart negotiations.
The source said Britain recognised Iran's right to nuclear power, but questioned the need for it to develop enriched uranium, given that Russia was already supplying its nuclear reactors with fuel.
Scott Ritter, a former UN weapons inspector, wrote recently: "The real purpose of the EU-3 intervention - to prevent the United States from using Iran's nuclear ambition as an excuse for military intervention - is never discussed in public." He added: "The EU3 would rather continue to participate in fraudulent diplomacy rather than confront the hard truth - that it is the United States, and not Iran, that is operating outside international law when it comes to the issue of Iran's nuclear programme."