Britain and its allies must be prepared to take or support military action against Iran as a last resort, MPs have insisted.

Midland MPs from all parties backed the Government’s policy of keeping “all options” open, amid fears that Iran is building nuclear weapons.

And they rejected demands from a Conservative backbencher that the Government “rule out” the use of force.

The overwhelming display of support for keeping the military option on the table came after UN nuclear inspectors arrived in Tehran for the second time in a month, to discuss the country’s nuclear programme.

Iran insists it is developing nuclear facilities for purely peaceful purposes.

However, the International Atomic Energy Agency, a United Nations watchdog, reported in November that it had information suggesting Iran had carried out tests “relevant to the development of a nuclear explosive device”.

In an attempt to pressure Iran into giving up its nuclear programme, the European Union has announced a boycott on Iranian oil beginning in July this year.

Israel has warned that it could use air strikes to destroy Iran’s nuclear facilities, and there has been speculation that the US and other western nations could directly take military action, or otherwise support action by Israel.

Debating the growing tensions in the Middle East, MPs rejected calls led by London Tory backbencher John Baron for the Government “to rule out the use of force against Iran and reduce tensions by redoubling diplomatic efforts”.

Instead, by a margin of 285 to 6, they voted for an amendment which backed “the Government’s efforts to reach a peaceful, negotiated solution to the Iranian nuclear issue through a combination of pressure in the form of robust sanctions, and engagement” but which also said the Commons “recognises the value of making clear to Iran that all options for addressing the issue remain on the table”.

Many MPs insisted they did not support force, but believed ruling out military action entirely would make it harder to resolve the issue.

Criticising Mr Baron, MP Steve McCabe (Lab Selly Oak) said: “I am afraid that this is sounding terribly like an appeasement argument.”

He said the West should look at ways “to support legitimate protest in Iran by the people who are pushing for regime change, whom we have supported in other countries and whom we should support in this instance.”

Bob Ainsworth (Lab Coventry North East), a former Defence Secretary, said: “The consequences of an American military intervention, let alone an Israeli intervention, in Iran would be profound and long-lasting, as has been said by many other Members, and it should be avoided. That is not to say that we should take the option of military intervention off the table. We are dealing with a police state.

“Iran is a proud country with a rich culture, a strong middle class and a young population, but they have been repressed by a bunch of paranoids.

“Yes, those people put a religious connotation on that, but we are dealing with a police state. History surely teaches us that we do not deal effectively with a police state by telling it before we even talk to it that, in the final analysis, if all else has failed, we will do nothing about it.”

James Morris (Con Halesowen and Rowley Regis) said: “We need to be clear about the danger that the world would face from a nuclear-armed Iran. As other Members have said, it is a state widely recognised as the world’s leading sponsor of international terrorism.

“It funds, trains and arms groups such as Hezbollah and Hamas... it would be a grim prospect for the cause of peace in the middle east if those terrorist groups gained the protection of an Iranian nuclear umbrella.”

Setting out his argument for ruling out the use of force, Mr Baron said: “A strike by Israel or the West would unite Iran in fury and perhaps trigger a regional war, and it would certainly encourage the hard-liners to push for a bomb. Despite that, the present policy is to refuse to rule out the use of force.

"Such a policy is not only naive, but illogical: we are keeping an option that we all know would be a disaster, against a country that chooses to ignore it, yet that option heightens tensions and makes a peaceful outcome less likely. That is nonsense.”

No West Midland MPs voted to retain the motion to “rule out the use of force”.