The Labour MP who questioned the loyalty of the British envoy to Israel has posited that the Iranian nuclear threat is "non-existent".

In Foreign and Commonwealth Office questions on Tuesday, Paul Flynn, the Labour MP for Newport West, referred to the 179 brave British soldiers who were lost in pursuit of non-existent weapons of mass destruction in Iraq.

"If the nuclear state of Israel attacks Iran in pursuit of non-existent long-range Iranian missiles carrying non-existent Iranian bombs, can we have a guarantee that the House would discuss its position before any British lives were put in jeopardy?" he asked.

Last year Mr Flynn caused a stir when he queried whether a Jewish diplomat should serve as the British ambassador to Israel. "Britain needed "someone with roots in the UK [who] can't be accused of having Jewish loyalty," he said, in widely condemned remarks.

In response to Mr Flynn's question on Iran, Foreign Secretary William Hague emphasised that if British forces were committed to military action there should be a parliamentary vote. But he cautioned against extrapolating too much from a comparison between Iraq and Iran.

"The position on Iran and its nuclear programme is documented in dramatically more detail than any of the programmes of Iraq discussed before the war in Iraq," he said.

Speaking in FCO questions on the Iranian nuclear programme yesterday, the prominent Israel critic and Labour MP Sir Gerald Kaufman asked Mr Hague to "make it clear to Israel and everybody else that we are totally opposed to military action against Iran?"

Mr Hague said that a "nuclear-armed Iran would result in still greater instability in the middle east and increase the risk of a nuclear arms race" but said that Britain had made it clear to Israel that it favoured "the twin-track policy of sanctions and negotiations" and opposed a military strike.