The Federal Reserve is already engaged in unorthodox “quantitative easing” and should prepare for the possibility that more extreme measures could be needed to guard against deflation, Don Kohn, its vice-chairman, said on Wednesday.

“We have already engaged in forms of quantitative easing,” Mr Kohn told the Cato Institute, a think-tank. He said the US central bank should consider “what other forms of quantitative easing might happen as a contingency plan”.