British politicians are downplaying the evidence for an Iranian nuclear threat on the basis of a comparison with the lead-up to the Iraq war. In doing so, they are criticising Israel for its approach to Tehran.

In Foreign Office questions last week, Labour MP Paul Flynn became the latest in a growing number to suggest that Israel and its allies were heading toward another self-interested Middle Eastern war based on spurious evidence. This is despite a recent report by the International Atomic Energy Agency that showed Iran to be advancing its nuclear programme, including doubling the number of centrifuges installed in an underground complex.

Referring to the 179 British soldiers lost "in pursuit of non-existent weapons of mass destruction in Iraq", Mr Flynn spoke of "non-existent Iranian bombs". The MP, who last year queried whether a Jewish diplomat should serve as the British envoy to Israel, asked for a guarantee of a parliamentary discussion "if the nuclear state of Israel attacks Iran in pursuit of non-existent long-range Iranian missiles".

Also last week Basildon and Bilericay Conservative MP John Baron questioned Foreign Secretary William Hague on discrepancies between CIA director General David Petraeus's views and the recent warning by MI6 chief Sir John Sawers that Iran could be a nuclear power within two years.

Mr Baron called the supposed difference of opinion "deeply troubling". "It suggests they do not agree on basic facts. Any military action by Israel or anyone else should therefore be out of the question."

In a debate he led earlier this year, Mr Baron said: "Much has been made of the circumstantial evidence and of western intelligence reports, but Iraq should have taught us to be careful about basing our foreign policy decisions on secret intelligence and circumstantial evidence."

Other British politicians have drawn the same conclusions, with Labour MP Jeremy Corbyn writing in the Morning Starof the "political hawks who assumed that Iran's "nuclear technology will be used to develop nuclear weapons." He then described his "awful feeling of deja vu back to 2002, when Blair and Bush almost single-handedly elevated Iraq from being a functioning, albeit authoritarian, state to one of existential enemy status for the West".

He added: "War duly followed".

Jenny Tonge, the disgraced Liberal Democrat peer, has accused Israel of attempting "to divert attention towards Iran, with talk of nuclear weapons, which is a scenario eerily reminiscent of the run-up to the attacks on Iraq in 2003."

The Stop the War coalition, which led protests against the 2003 invasion of Iraq, has been urging the West not to "Iraq Iran" and currently features a video on its website titled: "The Iran lie is same as the Iraq lie."

Dermot Kehoe, chief executive of Bicom, said: "There is really no comparison between the situation in Iraq and that in Iran", pointing to "the ample evidence that Iran is preparing the technology to construct actual nuclear weapons.

"Iran has been caught, repeatedly, secretly building facilities which are capable of producing nuclear weapons fuel and which are not consistent with a purely civilian nuclear programme," he pointed out. "This evidence was scrutinised for years by the IAEA - a cautious multilateral body not given to alarmism - before they declared it 'credible' in a detailed report published in November 2011. One would have to be blind, or looking the other way, not to see what Iran is up to."