US President George W Bush has spoken of the "undeniable" success of the invasion of Iraq on its fifth anniversary.

In a speech at the Pentagon, Mr Bush said: "Five years into this battle, there is an understandable debate over whether the war was worth fighting, whether the fight is worth winning, and whether we can win it.

"The answers are clear to me: removing Saddam Hussein from power was the right decision, and this is a fight America can and must win."

He added: "The successes we are seeing in Iraq are undeniable."

But the anniversary of the invasion that toppled the Iraqi dictator sparked protests against the ongoing Western military presence in the country.

Thirty-two people were arrested when they tried to block entrances to the Internal Revenue Service as part of a day of demonstrations in Washington DC.

Another group of protesters headed to Union Station in the US capital where they stood frozen on the spot to bring attention to their cause.

In London, anti-war campaigners will be staging a vigil outside Downing Street and plan to step up calls for British troops to be brought home.

CND, the Stop The War Coalition and the British Muslim Initiative are to deliver a letter to Prime Minister Gordon Brown demanding a public inquiry into the conflict.

The letter describes the Iraq war as "disastrous" and calls for March 20 to be declared International Peace Day.

The three groups are urging people to hold a minute's silence at 12 noon on Thursday in remembrance of the civilians and soldiers who have died in the conflict.

At least 3,990 members of the US military have died since the beginning of the war in 2003. It has cost taxpayers about $500 billion (£250bil) so far, and estimates of the eventual tab run far higher.

The Government said earlier this month that the cost of British military operations in Iraq is set to rise to more than £6.5 billion.

The British military death toll stands at 175.

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