The Bank of England got it about right when it opted to inject another 75 billion pounds into the financial system, a top policymaker said on Wednesday, adding the move will help fend off the risk of deflation.

I think 75 billion is about right, Bank policymaker Adam Posen told Reuters in an interview on the sidelines of the Economist's Buttonwood conference in New York.

It's a sensible amount and proportionate to the challenge we are facing.

The additional funds, part of the Bank's quantitative easing program, won't lead to an immediate boom but should fend off deflation risks, Posen said.

He dismissed concerns that the program would push up consumer prices, which rose 5.2 percent in the year to September, matching a high seen in 1997, and said he expected inflation to fall below the Bank of England's 2 percent target by the summer of 2012.

Posen said policymakers would review the policy in the months ahead before deciding what steps, if any, to take next.

It is possible to scale up quantitative easing if necessary, he said, adding that critics who say there are diminishing returns are misguided or delusional, as it's just monetary policy by another means.

(Reporting by Steven C. Johnson and Kristina Cooke; editing by Diane Craft)