Brown said it was time for a "new front" in British policy on Iraq and he would learn from mistakes that had been made there.
He said there should be greater emphasis on political reconciliation and economic development so Iraqis felt they had more of a stake in their future.
"Tony Blair's legacy is nothing but the Iraq war"
Politics, Cambridge, UK
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"I accept that mistakes have been made ... I'll be listening to what the government of Iraq say and what people on the ground say over the next few weeks."
Brown said he planned to visit the Middle East and British forces in the region in coming weeks.
He said he would consult the Iraqi government and people in the next few weeks and then suggest new ideas.
He said Britain would keep its obligations to the Iraqi people, but added he would look at new parliamentary procedures for dealing with peace and war - acknowledging public mistrust at the decision by Blair's government to go ahead with a very unpopular war.
The new policy would mean "everybody can be clear that there is full and open debate and proper accountability of government in all these major decisions," he said.
Asked if British policy on Iran was working, Brown said he believed existing sanctions were having an effect and would not shy away from ratcheting them up if needed.
The British government's role alongside the US and support for the 2003 invasion of Iraq, as well as its domestic policies, have seen its popularity slide.
The Labour party has now fallen been behind the Conservative party in opinion polls for the past year. General elections are not expected before 2009.