The head of the British army has defended his comments that UK troops "exacerbate" security problems in Iraq and should withdraw "sometime soon".
General Sir Richard Dannatt said he backed "what is right for the Army" and denied a "chasm" with the government.
Downing Street said the general had Tony Blair's full support, and the Iraqi government wanted troops there.
A spokesman for the Iraqi president said the departure of multi-national troops now "would be a disaster".
'See this through'
In a Daily Mail interview, Sir Richard, who took on his role in August, said UK troops should "get ourselves out sometime soon because our presence exacerbates the security problems".
He also said: "I don't say that the difficulties we are experiencing round the world are caused by our presence in Iraq but undoubtedly our presence in Iraq exacerbates them."
And he said planning for what happened after the initial successful war military offensive was "poor, probably based more on optimism than sound planning".
He later told the BBC Radio 4 Today programme that when he talked about pulling out of Iraq "sometime soon", he meant "then when the mission is substantially done we should leave".
"We don't want to be there another two, three, four, five years. We've got to think about this in terms of a reasonable length of time."
He said the view that the presence of UK troops "exacerbates" the problems was "not right across the country", but in parts of it.
And he later said in a statement: "I'm a soldier - we don't do surrender, we don't pull down white flags. We will remain in southern Iraq until the job is done - we're going to see this through."
Downing Street queried the way the chief of the general staff's original statements, in the Daily Mail, were presented.
A spokesman said Sir Richard was "actually saying what government policy is.
"We don't want to be there any longer than we have to, but ultimately that is a decision for the Iraqi government."
The spokesman for Iraqi President Jalal Talabani, Kamran Karadahi, said: "They are still needed very much to help Iraq. The British troops in the south have done a very good job and are still doing so."
He added: "We do not believe the presence of multi-national troops is really the reason for the violence. It is the insurgents, terrorists, al-Qaeda etcetera."
"We - the Iraqi government, the British, and the multi-national forces (MNF) have the shared goal of helping democracy to succeed in Iraq, and this is very important."
Most of the British forces in Iraq are based in Basra
A Ministry of Defence spokesman said Britain had "a clear strategy" and worked with international partners "in support of the democratically elected government of Iraq, under a clear UN mandate".
The former Conservative Defence Secretary, Sir Malcolm Rifkind, said: "What he said was actually blindingly obvious and what the vast majority or people would also agree with".
Liberal Democrat leader, Sir Menzies Campbell, called such an intervention by a senior military figure "unprecedented" and said the government had an "overwhelming obligation" to listen to him.
Anti-war campaigners welcomed Sir Richard's comments.
Rose Gentle, whose soldier son was killed in Iraq, said: "I'm just really delighted that Sir Richard Dannatt has stood up and spoken out. He is protecting our boys."
There are currently more than 7,000 British soldiers in Iraq, based largely in Basra in the south of the country. Since the invasion in 2003, 119 British troops have been killed, most of them in southern Iraq.