UK Foreign Secretary Jack Straw has insisted he respected the opposition of France to the Iraq war.
Britain and France need to have good relations
Relations between the UK and France were strained before the start of the Iraq war when the French said they would not back a second UN resolution.
Mr Straw was speaking to mark the centenary of the 1904 entente cordiale treaty between the two countries.
He said any disagreements stemmed from a different understanding of how the will of the UN is best enforced.
But despite a growing belief among many members of the public in Britain and elsewhere that no weapons of mass destruction will ever be found, Mr Straw was bullish over the war.
And he argued not using military action to back up the UN's demands to Iraq over weapons programmes would have meant international law was a "dead letter".
Mr Straw said: "Our differences over Iraq were, in essence, differences over how best to maintain the authority of international rules.
"I respect the position which France took, and it is a matter of regret to me that we were divided over it.
"But Britain went to war in Iraq, as a last resort, because Saddam Hussein was still defying the international community after 12 years of discussion and
17 UN resolutions.
"We felt that international law without enforcement would
become a dead letter."
Mr Straw said the UK and France had now found common ground in their desire to bring security, prosperity and democracy to Iraq.
The foreign secretary also spoke of the battle to secure a new European constitution.
He warned: "We need to keep the EU focused on delivering reforms which will create more jobs and higher growth."