A total of 53% of voters believe war was baseless with 38% backing the conflict, according to the ICM poll published in the London-based Guardian newspaper on Tuesday.
Immediately after the US-British occupation of Baghdad in April, British public support for the war stood at 63%, falling to 51% in July.
The latest poll’s findings are a further blow to Prime Minister Tony Blair, who is facing the biggest crisis of his six-year tenure over the suicide of David Kelly, the British scientist at the centre of a BBC report that London exaggerated the alleged threat posed by Iraq.
The fallout from Kelly’s suicide and opposition to the invasion of Iraq has resulted in the lowest voter support for Blair’s ruling Labour party in more than a decade, according to British media reports.
Only 35% of voters are willing to back the party in the next general election, due mid-2006 at the latest, according to the ICM survey.
However, Labour has managed to hold on to its five percentage point lead over the opposition Conservatives since last month.
Britain’s third main party, the Liberal Democrats, have made significant gains following victory last week in a key London by-election, which saw them wipe out a large Labour majority.
The telephone survey of 1002 adults was conducted last weekend following Labour’s humiliating defeat in the by-election.
Meanwhile, US President George Bush's approval rating has hit a new low, with only half of Americans saying they liked the way he was handling his job.
That's down from 71% in late March, according to a USA Today/CNN/Gallup survey.
The survey also found for the first time that a Democratic
candidate could beat Bush if the next presidential election were held today.
Former NATO commander Wesley Clark would beat Bush 49% to 46%, and Senator John Kerry would win 48 to 47%.