Activity in Britain's services sector increased at the fastest rate since May 1997 last month, raising the prospect of a big jump in economic growth in the final three months of 2013, a closely watched survey showed on Tuesday.

Financial data company Markit said its services purchasing managers' index (PMI) rose to 62.5 in October from September's 60.3, easily beating economists' forecasts for a fall to 59.8 and increasing the chance that the Bank of England will revise up its quarterly growth forecasts next week.