Brown dismissed as "irresponsible" comments from opposition Conservative leader David Cameron that Britain was running the risk of being forced to go to the International Monetary Fund to prop up its economy -- a humiliation suffered under a previous Labour administration in 1976.

The ONS said the decline in fourth-quarter output was driven by a sharp contraction in both services and industrial production.

The services sector, which accounts for three-quarters of the economy shrank by 1.0 percent in the fourth quarter, the fastest pace since 1979. Industrial production suffered its biggest fall since 1980. (Editing by Stephen Nisbet)