London: Britain's top financial regulator announced he was to step down, surprising markets and casting doubt over the future of the Financial Services Authority (FSA) and an overhaul of the sector.

Hector Sants, a former investment banker well-respected in the industry, will leave the FSA just after a general election widely expected to leave the opposition Conservatives in power.

The Conservative Party, a long-time leader in opinion polls, has said it wants to abolish the FSA and hand its banking supervisory powers to the Bank of England, saying the regulator failed to spot problems ahead of the financial crisis and was unable to avert a costly bailout.

Sants, who will leave in the summer, said he had always planned to hold the post for three years. But the FSA did not outline a succession plan yesterday and said the process for picking a successor would be announced "in due course". It remains to be seen whether Sants could be tempted to join a reshuffled regulator at a later date.

Sants has publicly criticised plans to overhaul the country's regulatory system at a critical time, warning it could mean losing lessons learnt over the past two years.