Senior U.S. Federal Reserve official Charles Plosser warned on Thursday of the risks to future inflation from its program of quantitative easing and reiterated that the bar for more stimulus for the economy was very high.

Charles Plosser, President of the Philadelphia Federal Reserve Bank and a policy voter at the Fed this year, said he believed that as the US economy improved, the potential for a rise in inflation was quite large.

There's about 1.5 trillion dollars of what we call excess reserves in the banking system: they're just sitting there, they're not creating inflation, at least not yet. But they do have the potential to do that, he told Britain's BBC radio.

Plosser, a well-known inflation hawk, also reiterated that the recovery in the United States would be long and slow and that growth this year had been undermined by external, temporary factors including Japan's tsunami disaster.

I don't think it's going anywhere very quickly but I do think that as the economy recovers .... that the amount of money we have in the system that has the potential to create inflation is quite large, Plosser said.

Asked if there would be a third round of quantitative easing, Plosser added: I think the hurdle is very high.

(Writing by Avril Ormsby and Jodie Ginsberg; Editing by Patrick Graham)

Japan United kingdom Quantitative easing Inflation