Mr Blair says the Iraqi leader has clear ambitions to get nuclear capability to add to his existing stockpile of chemical weapons.

Be in no doubt at all that he is certainly trying to acquire weapons of mass destruction, in particular a nuclear capability

Tony Blair

Iraq is also believed to have a biological capability.

Mr Blair said last week that the Iraqi leader's weapon ambitions represented a gathering threat and that 11 September had shown some security threats were so dangerous they had to be tackled pre-emptively.

In an interview for next month's issue of the centre-left Prospect magazine, Mr Blair suggested that in the case of Iraq the threat could go nuclear as well as chemical.

The prime minister was questioned about suggestions that US President George W Bush was preparing to take action to oust the Iraqi dictator.

Nuclear

Mr Blair said: "If the time comes for action, people will have the evidence presented to them.

"But be in no doubt at all that he is certainly trying to acquire weapons of mass destruction, in particular a nuclear capability."

During the interview Mr Blair acknowledged there was a "certain scratchiness" in relations between the EU and US.

He insisted that ideologues of both right and left wings were exaggerating the differences and thus making the world a "much more dangerous place".

Strong institutions

Mr Blair said: "If we want to have greater sway and greater power, then instead of complaining about America, we've got to face up to what we need to do.

Pre-emptive strikes may be necessary

"That means developing a coherent defence capability and a set of institutions to allow Europe to speak strongly."

The prime minister also confirmed his support for the creation of a political president of the European Commission.

He argued that the current arrangements under which the presidency of the council of ministers rotates every six months was "absurd."

There has been speculation that Mr Blair harbours ambitions for such a post.

Third way

Asked specifically about that he said: "No, that's not the issue."

Mr Blair was also asked about the issue of asylum seekers in the magazine interview.

He said that the existing system for dealing with people seeking asylum was "fashioned for a different world".

The prime minister was also quizzed about the "third way" - the political philosophy with which he tried to put old idealisms behind him and his party.

"I would still defend it; indeed I could explain every part of what the government is doing today in third way terms," he said.

"You cannot be a government that redistributes wealth and opportunity unless you're running a strong, fiscally disciplined economy.

"You won't get public services turned around unless they are based on consumers.

"And you can't be a serious player in the world unless you're strong on defence."