* Sees UK recession as deep as major post-war downturns
* Says significant policy easing will take time to work
* Warns against "heavy-handed regulatory interventions"
LONDON, Dec 9 (Reuters) - The economic recession gripping the UK is likely to be as long and deep as the previous three major post-war downturns in the mid-1970s, early 1980s and early 1990s, Bank of England (BoE) policymaker Andrew Sentance said.
Speaking at a monetary policy and markets conference in London on Tuesday, Sentance also said the BoE had delivered a significant relaxation of monetary policy but that this would take time to have an effect.
The BoE last week cut interest rates by one percentage point to 2 percent, their lowest level since 1951 and indicated more needed to be done to lessen the impact of the economic downturn.
The BoE's November Inflation Report forecast a recession that was slightly less deep than in the three major post-war UK downturns.
"However, recent survey data have been weaker than that forecast implied and so I now expect the recession to be of comparable depth to those previous downturns," Sentance said.
He said that in the short term the challenge for monetary policy was to counter the impact on demand from the global banking crisis and to head off potential deflationary risks.
In the longer term, policymakers needed to develop better instruments for maintaining the stability of financial systems.
Monetary policy cannot do this unaided, Sentance said, but he also warned against "heavy-handed regulatory interventions".
"We need to take time to decide what a new regime for regulating the financial sector looks like," he said. (Reporting by Mark Potter, Editing by Stephen Nisbet)