The United Nations Secretary General, Kofi Annan, has said that the war in Iraq has done little to increase security across the world.
In an interview on British television, Mr Annan said the international community now had a lot to do to improve security.
Mr Annan has already angered the Bush administration in the US by saying he regarded the conflict with Iraq as illegal.
In comments that are likely to antagonise Washington further, Mr Annan said that the invasion of Iraq also had not halted the activities of international terrorists.
Meanwhile in London, tens of thousands of anti-war demonstrators have taken to the streets of London to call for the withdrawal of troops from Iraq.
The protest, organised by the Stop the War Coalition, was supported by Paul Bigley, whose brother was abducted and killed in Iraq.
The British ambassador to Iraq, Edward Chaplin, who urged people to support the march, has made a televised appeal to Iraqis for help in finding the 62-year-old engineer's body.
He urged them to honour the holy month of Ramadan by coming forward with any information.
