British Prime Minister Gordon Brown's party is still flailing in the domestic opinion polls, as he prepares to host the G20 summit this week that could plot the way out of the global economic downturn.

His governing centre-left Labour Party is 13 percent behind the main opposition Conservatives, according to a survey by pollsters ICM in The Sunday Telegraph newspaper.

The poll put the centre-right Conservatives up four percentage points from last month on 44 percent, Labour up three on 31 percent and the centre-left Liberal Democrats down four on 18 percent. Other parties registered eight percent collectively.

Drumming up support for his G20 agenda, Brown went on a whirlwind tour last week that took him to the European Parliament in Strasbourg, France; to meet top bankers in New York; for talks with Brazilian President Luiz Inacio Lula da Silva and to a conference of centre-left leaders in Chile.

Brown is hosting the Group of 20 summit of world leaders at the ExCeL exhibition centre in east London on Thursday, with all eyes on whether leaders can agree a common approach to fixing the financial crisis.

Brown must call a general election by May 2010 at the latest and most commentators believe he will hold off till then.

ICM interviewed 1003 random adults by telephone on Wednesday and Thursday.

Meanwhile the Conservatives' top donor Stuart Wheeler defected to the United Kingdom Independence Party, a fringe group dedicated to pulling Britain out of the European Union.

Wheeler, who made his fortune in spread betting, gave the Conservatives five million pounds in 2000, the biggest-ever donation to a British political party.

"The EU is doing so much damage to our economy and our way of life that I can no longer vote Conservative at the European elections," he said.