"How long we stay there is going to be event driven," General Mike Jackson told Britain's Independent newspaper in an interview published on Monday.
"The mission is to provide Iraq with its political and economic future."
He raised the prospect of more British soldiers being redeployed from the relative calm of their southern base in and around Basra.
Any such move would be deeply unpopular in Britain, where opinion polls suggest most people are against the war in Iraq.
British Prime Minister Tony Blair, already facing a backlash over his support for the Iraq war, was criticised in parliament last month for the redeployment of 850 soldiers to a volatile area near Baghdad.
The move, attacked by critics for exposing the Black Watch troops to danger levels much higher than in the south, freed up US forces for an offensive in Falluja.
Four British soldiers have died in bombings since moving north.
There has been mass opposition
to Britain's involvement in the war
Jackson said all British operations had been in the Basra area until "this one-off deployment", adding: "That is not to say, in the future, there may not be a military requirement of the coalition as a whole for a British unit or units to be elsewhere."
Britain, which has 8500 soldiers in Iraq and was the United States' main ally in the 2003 invasion to topple former Iraqi president Saddam Hussein, has lost 74 soldiers in Iraq in the past 20 months since the invasion.
Jackson said his troops were fighting a small group opposed to change in Iraq, which is due to hold elections in January.
"I believe a pretty small minority of Iraqis with some outside assistance cannot face the idea of progress in Iraq and are prepared to do some pretty revolting things to prevent it,"