Britain's economy is tipping headlong into a recession that could last more than a year and cost hundreds of thousands of jobs, warns Professor David Blanchflower, a member of the Bank of England's interest rate committee, in an interview with the Guardian today.

Blanchflower says the Bank must cut interest rates rapidly to prevent the downturn being too painful, and thinks the UK could be in for a worse time than even the United States, where interest rates have already been slashed and taxes cut to stimulate the economy.

The economist said the recent rises in unemployment are "the tip of the iceberg". The number of people out of work and claiming benefit is 840,000 but the broader measure of unemployment is 1.6 million, 5.2% of the workforce. Blanchflower said it could climb to more than 7% - a figure that would mean several hundred thousand people losing their jobs.

His warning comes days after the chancellor acknowledged that the slowdown could be "profound" and hinted he would change the Treasury's fiscal rules as the slowing economy looks set to bust them.

Today a leading thinktank, the Ernst & Young Item Club, says the economic outlook for Britain is like a "horror movie" as a result of the credit crunch and tumbling house prices.

Blanchflower has been voting for interest rates cuts for nine months but is unhappy that the other eight members of the monetary policy committee are reluctant to cut rates. "I think we are going into recession and we are probably in one right now. It's not too late to stop it but we have to act right now. Monetary policy has been far too tight for too long."

He wants interest rates cut sharply and says his colleagues should worry less about the recent rises in inflation, which he thinks will be temporary.

The MPC has cut rates three times since the end of last year to the current 5% level.

The last reduction was in April, but in May and June the other eight members did not follow Blanchflower in voting for further cuts. The this month's vote will not be announced until Wednesday.