By Daniel Bentley, PA Political Correspondent
Tony Blair faces calls today to avert military action against Iran as a broad coalition of organisations warns it would be disastrous.
The Prime Minister is urged to pressure the US to enter direct talks with Tehran and avoid the ''unthinkable'' consequences of war.
The move comes amid heightened tensions between Washington and Iran with the US appearing increasingly exasperated with the Middle Eastern state's nuclear ambitions.
President George Bush's criticism of alleged Iranian support for insurgency in Iraq has also revived concerns that his administration is gearing up for a possible attack.
Mr Blair is today accused by the alliance of charities, faith groups and other organisations of keeping open the prospect of military action as a negotiating tool.
In a report entitled Time to Talk: The Case for Diplomatic Solutions on Iran, they argue the Government should be trying to secure face-to-face talks between the US and Iran.
Speaking ahead of its launch today, former Labour minister Stephen Twigg, director of the Foreign Policy Centre, said: ''The consequences of military action against Iran are not only unpalatable, they are unthinkable.
''Even according to the worst estimates, Iran is still years away from having a nuclear weapon.
''There is still time to talk and the Prime Minister must make sure our allies use it.''
Other signatories to the report include charities Oxfam, the Unison, GMB and Amicus unions, the Muslim Parliament and Christian Solidarity Worldwide.
The report warns military action could further destabilise the region and provoke retaliatory attacks against British forces in Iraq and Afghanistan.
It could also undermine the war on terror by fuelling anti-western sentiments, while strikes against nuclear facilities risk unleashing radioactive contamination.
''Military action is not likely to be a short, sharp engagement but could have a profound effect on the region, with shock waves felt far beyond,'' the report says.
''Real diplomatic options still exist, if a face-saving solution can be found to convince the protagonists to approach the table. The possible consequences of military action could be so serious that governments have a responsibility to ensure that all diplomatic options have been exhausted.
''At present, this is not the case.
''The UK Government is well positioned to articulate objections to military action. Military action against Iran would work against the interests of the UK.
''The UK should not lose this opportunity to advocate for direct US engagement; strengthening the hand of reformists inside Iran by being seen to treat it fairly and thereby laying foundations for a more functional relationship with Iran in the future.''
The report says that Mr Blair is among several world leaders who are keeping military force on the table.
''Opposition to military action is currently widespread, though key leaders (notably Tony Blair and Angela Merkel) have refused to rule it out, believing the threat to be an important negotiating tool,'' it says.
Sir Richard Dalton, the British ambassador to Iran until last year, said that patience and diplomacy were key to securing a successful outcome.
''Given Iranian defiance of the Security Council, there is bound to be a break in the negotiations on the nuclear issue.
''But both sides should work for a resumption. It is vital that the US becomes fully involved in creative diplomacy.
''Recourse to military action - other than in legitimate self-defence - is not only unlikely to work but would be a disaster for Iran, the region and quite possibly the world.''
Leading American former military leaders issued a similar call yesterday in an open letter to a Sunday newspaper.
But the Tories said it was important to ''keep all options on the table''.
Shadow defence secretary Liam Fox said: ''We cannot give them the comfort of believing that there is any weakness in the western alliance or that there is a chance that they might be able to divide and rule.
''That is why it is important to keep all the options on the table.
''We have said this week...we should be tightening the financial sanctions from Europe to bring us in line with the United States so that they (Iran) can't see that there is any division between us.
''However we do think that as we kept strong diplomatic ties open with the Soviet Union at the height of the Cold War...we think there is room for better dialogue with Tehran.''
Liberal Democrat foreign affairs spokesman Michael Moore said: ''This is a timely and significant report. It highlights the need for the international community to be more aware of the potentially disastrous consequences of military action against Iran.
''The degree of support for this report is significant. It demonstrates the deep concern shared by different sections of society and across the political divide, on the deterioration in the nuclear dispute and the deep unease at the prospect of military action.''
Former Labour MP Lorna Fitzsimons, chief executive of the Britain-Israel Communications and Research Centre (Bicom), warned that ''time is running out'' to stop Iran becoming nuclear-armed.
Ms Fitzsimons told BBC Radio 4's Today programme: ''What we are talking about here is Iran reaching the ability on an industrial scale to manufacture highly-enriched uranium.
''IISS (International Institute for Strategic Studies) and many others prophesise that that is going to happen between nine to 11 months from today.
''That is the watershed. There is no return from that point. You can't get the genie back in the bottle technologically once they have sorted out the problem they currently have with their centrifuges.
''I don't think you can stop it. You might be able to disrupt it. It's a question of looking at how far you can go down the line where lose the ability to disrupt it.''
Ms Fitzsimons recalled that Israel took military action to target Saddam Hussein's nuclear research programme in Iraq long before the dictator was in possession of an actual bomb.
Speaking at the launch of the report in London, Sir Richard said it was vital to learn from the consequences of previous British military action in the region.
''The UK in the last century and this has intervened forcefully in the Middle East on several occasions.
''The lessons are that only when we do so in accordance with international law and with the principles of justice, with wide support in the region and with a well-thought out policy based on what is going to work practically, will we succeed in our aim.
''Supporting the US or Israel if they mount an attack on Iran before the steps suggested in this report have been taken would be wrong.''
The report offered a ''major and helpful contribution to the public debate which is so essential'', he said, calling for an inquiry by the House of Commons foreign affairs committee.
He said he believed it was for Iran to take the first move by suspending uranium enrichment.
''Thereafter there is much more the US could and should do in its own and the general interest to promote more responsible behaviour by Iran,'' he added.
Oxfam's Middle East director Adam Leach warned of ''horrific and horrendous'' humanitarian consequences of any military attack.
It also risked increasing the terror threat in the UK and causing huge damage to the economy, he said.
Ms Fitzsimons, speaking after the report's publication, added: ''The only way economic and diplomatic sanctions will work is if Iran realises that the credibility of a military strike is real.
''Iran thinks the US is weak and that Iran is in the ascendancy in the Middle East. That is why Iran's leaders do not feel the pressure or the need to work with the IAEA.
''Iranians view their enrichment programme as central to their pride and economic future.
''Therefore, it does not matter whether it is Ayatollah Khamenei, Ahmadinejad or Rafsanjani fronting their nuclear campaign; this is about Iranian destiny.
''The international community must do all they can to make sure the soft power options of sanctions and diplomacy prevent the unthinkable.
''The only way to make soft power a success in Iran is to ensure they realise that the hard power of military actions is a last resort reality.''
