LONDON (Reuters) - Britain's recovery gathered pace in the three months to April, a leading economic think tank said on Thursday, but it warned that the statistical effect of a weak January had flattered growth in the following three months.

The National Institute for Economic and Social Research, Britain's leading macro-economic think tank, said the economy grew 0.8 per cent in the three months to April after expanding by 0.3 per cent in the three months to March.

"Things haven't suddenly taken off in the way the headline figure suggests," said Mr Jonathan Portes, director of the economic think tank.

"The data has improved a little but we would still describe this as a relatively slow recovery."

Britain's central bank refrained from injecting further cash in the economy earlier on Thursday, opting to wait and see if recent initiatives to boost lending will allow the recovery to gain traction.