UK Foreign Secretary Jack Straw has said the upsurge in violence against coalition troops in Iraq is the "most serious" threat faced since war ended.
Jack Straw blames the current crisis on Saddam Hussein
He was speaking to BBC News one year after Saddam Hussein's fall and as the situation in Iraq worsens.
US forces are besieging the Iraqi town of Falluja in a five-day battle which has so far left up to 300 Iraqis dead.
Meanwhile, a British man has been shot dead in Iraq whilst he was guarding electrical workers for a US company.
Mr Straw said "the lid of the pressure cooker has come off," but he blamed events on the Saddam regime's legacy.
"Some of the tensions and pressures which were there, and would have come out in any event, have to a degree been directed towards the coalition."
Mr Straw was asked on BBC Radio 4's The World at One programme whether he imagined a year ago that things would get as bad in Iraq as they have
been over the last week.
"No I didn't. I thought that they would go from some good days and some bad days. There is
no doubt that the current situation is very serious."
But he insisted Iraqis were still better off now than they were a year ago.
"I don't want to minimise the problems that we face, they are serious but they have to be seen in a context, in which Saddam held Iraq in a reign of terror," he said.
"These insurgents are an enemy of the majority of Iraqis as much as they are fighting coalition forces.
"We need to be aware that the vast majority of Iraqis, whilst they do not like the occupation, they like the fact that Saddam has gone.
"They are desperate for a smooth transition of power to a representative and then a democratic government with the Iraqis writing their own constitution," he said.
Tony Blair's office said he would meet UN secretary general Kofi Annan in New York on 15 April and President Bush in Washington on 16 April.
Two Labour MPs opposed to the war in Iraq have demanded the recall of parliament on Monday because of the "dire" situation in southern Iraq.
Tam Dalyell and Alice Mahon said an "an absolutely crucial week" lay ahead in Iraq, and parliament should be sitting.
Liberal Democrat foreign affairs spokesman Sir Menzies Campbell told the BBC it should be made clear the occupation was only temporary.
"Let's show some signs of wanting to get on with the elections, otherwise the inference will be that we are content to continue with occupation," he said.
The call comes after British civilian Gary Teeley, 37, was kidnapped in Nasiriya, the scene of heavy fighting between radical Shia militiamen and Iraqi troops.
Separately, the British man shot dead while guarding workers to safety in Iraq has been named as Michael Bloss, an ex-member of the Parachute Regiment.
The 38-year-old moved to the US where he started working for a company called Custer Battles.
He was originally from Bridgend in South Wales and his father, Peter, said that he hoped to fly his body home next week.
Hundreds of UK troops set off for duty in southern Iraq on Thursday to relieve existing peacekeeping forces.