The prime minister has defended his relationship with the US in a bid to win over voters critical of his stance on Iraq.

Tony Blair was speaking ahead of Thursday's triple council, London and European elections and urged voters to cast their ballots on local issues.

But in an attempt to dissuade the public from punishing him for his controversial foreign policies he backed Britain's close alliance with America.

"In the end, the relationship with America is of huge importance to this country and its security, and indeed its prosperity," Blair told GMTV on Monday.

"I took the view, and I still take the view, that there's a big threat from terrorism and these unstable states out there," he added.

"Saddam was an evil dictator. If you talk to anybody in Iraq today, whatever the problems, they realise that getting rid of Saddam Hussein is the start of rebuilding this country and possibly making it a stable force in the Middle East."

The prime minister again acknowledged that the post-war difficulties in Iraq were making it hard for Labour to set out its case to voters.

However he urged the electorate to vote on the issues local authorities actually have control over.

"In the end, the real question for people is: Are we right in saying that we have a different type of threat in the world today?" Blair said.

"If you answer is yes, then sticking with America and seeing it through is the right thing to do.

"In the end, the problem we have is not a very complicated one.

"People do see a strong economy, they see the investment in the public services, but there is this Iraq issue hanging there. I still believe we did the right thing.

"What people should do is vote on the local services because there are clear differences between the main two parties."

Blair also admitted apathy is hitting the European parliament poll because "it all seems so far away", but he attacked eurosceptic parties which encourage disengagement.

"Whatever difficulties there are about being part of the European Union, 60 per cent of our trade is with the EU," he said.

"Therefore it's not very sensible for us not to be part of the EU."