NORTH-East MPs raised the alarm last night after Tony Blair refused to rule out support for an American nuclear strike against Iran.

The Prime Minister told MPs it was "perfectly sensible" for President Bush to leave all options on the table if Iran failed to halt its suspected nuclear weapons programme.

A leading US investigative journalist has claimed those options include the use of a tactical nuclear weapon against deep Iranian bunkers.

Speaking in the Commons, Liberal Democrat leader Sir Menzies Campbell asked Mr Blair: "Is there any military option, including nuclear weapons, that you would rule out?"

The Prime Minister replied: "Nobody is talking about a military invasion of Iran, or military action against Iran."

But he added: "The President of the US is not going to take any option off the table.

"That's perfectly sensible, for all the reasons that have been given many times by the President himself."

The comments were in sharp contrast to Foreign Secretary Jack Straw's description of the idea of a US nuclear strike as "nuts".

Blaydon MP David Anderson said he recognised that attempts to prevent Iran developing nuclear weapons were inevitably a "game of bluff and double-bluff". But he said: "This is very dangerous ground to go down. It will do nothing to lower tensions."

Sharon Hodgson, MP for Gateshead East and Washington West, said: "We need to have restraint dealing with Iran and do nothing without the authority of the UN."

And Sir Menzies said: "If ever there was an issue which required clarity, it is this. The Prime Minister's ambiguity will only fuel suspicion."

Mr Anderson and Ms Hodgson are among 23 MPs who have signed a parliamentary motion calling for "further dialogue between Iran and the international community".