LONDON - British Prime Minister Gordon Brown has fallen further behind the opposition Conservatives to trail by 18 percentage points after his government announced a record budget deficit, an opinion poll showed on Friday.

If the result was repeated at the next election, due by June 2010, the Conservatives would beat Brown's Labour Party by a landslide and return to power for the first time since 1997 with a 150-seat parliamentary majority.

In the first opinion poll since finance minister Alistair Darling unveiled Britain's worst economic performance since World War Two on Wednesday, Labour slipped four points to 27 percent, with the Conservatives up four on 45 percent.

It is the biggest lead for the center-right Conservative Party in the YouGov/Daily Telegraph newspaper survey since last September. A separate poll by ICM in the Guardian newspaper the day before the budget put the gap at 10 points.

Brown, a former finance minister who has staked his political reputation on his handling of the economic crisis, was losing voter support on the economy, the YouGov poll suggested.

Asked which party would do a better job with Britain's finances, 39 percent backed the Conservatives, up four points on last month, compared to 24 percent for Labour.

Brown's personal ratings also took a knock. Some 69 percent were dissatisfied with his performance as prime minister, a rise of four percent on last month.

By contrast, Conservative leader David Cameron saw his personal standing climb by seven points to 56 percent, a rise described by the Conservative supporting Daily Telegraph as a Budget Bounce.

There was better news for Labour's announcement of a rise in the top income tax rate in Wednesday's budget. The poll found 68 percent agreed with raising the rate to 50 percent for those earning 150,000 pounds ($218,500) or more.

Another poll in Friday's Times newspaper found a majority (57 percent) in favor of the higher tax. However, the Populus poll said nearly two-thirds expected the economy to worsen in the next three months.

Darling said the British economy could shrink by 3.5 percent this year, the worst decline since the war, although it should pick up toward the end of the year.

That would come as a welcome relief for Britons struggling to cope with falling house prices, low returns on savings and rising unemployment. Figures released just before the budget said 2.1 million people were out of work, a 12-year high.

* YouGov surveyed 1,896 adults on Wednesday and Thursday; Populus polled 518 people late on Wednesday.