The US economy should accelerate in the second quarter to an annual growth rate of 3% or more, but it may not be clear for some time if the pick-up is sustainable, said a Federal Reserve official yesterday.

Global financial stability is at risk as central banks draw back from ultra-easy policies that have flooded the world with cash, because emerging markets lack defences to prevent potentially huge capital outflows, top officials have been warned.

Wall Street gave up a substantial early gain and staggered to a mixed finish today after a Federal Reserve official warned that interest rates might continue to climb.