There are about 7,000 British troops deployed in Iraq

Blair/Maliki briefing

Mr Blair told troops it was vital to "stand up and fight" for people of tolerance and moderation.

Earlier in Baghdad, Mr Blair said Britain would stand "four-square" behind the Iraqi government in its battle to defeat terrorists.

His trip to Iraq follows visits to Egypt and Turkey as part of a tour of the Middle East.

Mr Blair told the troops: "Our country and countries like it are having to rediscover what it means to fight for what we believe in.

"All over the world the same struggle is going on and if we don't stand up and fight for the people of tolerance and moderation who want to live together, whatever their fate, then the people of hatred and sectarianism will triumph."

We will continue to support you all the way in that endeavour which is important for Iraq, important for the region and important for the world

Prime Minister Tony Blair

He added: "This is real conflict, real battle, and it is a different kind of enemy - not fighting a state, but fighting a set of ideas and ideologies, a group of extremists who share the same perspectives."

Mr Blair has visited the now 7,000-strong UK contingent every Christmas since the 2003 war began.

Earlier, he met Iraq's leaders as part of his Middle East tour.

He said the security handover operation in Basra was going well but said troops would remain until the job was done.

His trip came as gunmen staged a mass kidnapping at the office of the Iraqi Red Crescent in central Baghdad, seizing up to 30 male staff and visitors.

And the prime minister has faced criticism for not going to Syria during his latest diplomacy mission.

Abdullah Dardari, Syria's deputy prime minister for economic affairs, said his country was part of the solution in bringing peace to Iraq and the wider region.

Support pledge

At a joint press conference with his Iraqi counterpart Nouri Maliki, Mr Blair said Britain was determined that attempts to establish democracy in the country would not be destroyed by terrorists or sectarian violence.

Describing the talks with the Iraqi prime minister, Mr Blair said he had reiterated Britain's determination "to stand four-square" behind the fledgling government and the Iraqi people.

He wanted to ensure that democracy was "not destroyed by terrorism, by sectarianism, by those who wish to live in hatred rather than peace".

He added: "We will continue to support you all the way in that endeavour which is important for Iraq, important for the region and important for the world."

Troop withdrawal

He defended plans for a gradual withdrawal of British troops from Basra in the south of the country and said it was not a change in direction.

Mr Blair wrote a message to the troops on the side of a tank

"This isn't a change of our policy," he said.

"This is our policy. Our policy is that as the Iraqi forces are capable of taking over control of the city of Basra so our forces stand back and go to a support role."

He added that there was a "very strong obligation for all countries in the region to be supportive of the [Iraqi] prime minister and his government".

Mr Maliki said he also thought it was a "regional and international responsibility" to protect Iraq from those who "don't want to see democracy in this country".

Mr Blair paid tribute to Mr Maliki's "courage" through what he described as "difficult and challenging times".

'Deteriorating situation'

Mr Blair's trip follows calls from the Iraqi prime minister for former members of Saddam Hussein's army to return to the military.

Mr Blair met Iraq's leaders as part of a tour of the Middle East

Sectarian violence is currently claiming as many as 100 lives a day and last month's report by the Iraq Study Group, led by former US Secretary of State James Baker, described the situation in Iraq as "grave and deteriorating".

Andrew North, the BBC's correspondent in Iraq, said the situation in the country had deteriorated significantly since the prime minister's last visit six months ago.

Baghdad is the third stop on Mr Blair's Middle East tour, during which he hopes to kick-start the peace process.

He has also been to Turkey and to Egypt, where he said the Middle East region faced a "critical moment of decision" and resolving the conflict between the Israelis and the Palestinians was crucial to stability.

He also called for international support for Palestinian President Mahmoud Abbas.