Aviva chief executive Mark Wilson is standing down after more than five years at the helm.

The Norwich-based insurer said on Tuesday that Mr Wilson would leave his executive role immediately but will remain with the group until a successor is appointed in April 2019.

It came as the group hailed a successful turnaround, which culminated in a pledge in its spring results to deploy £2bn of excess capital.

Mr Wilson said the company had come a long way from its 'poor' state of health when he took the top job.

Chairman Sir Adrian Montague will assume executive responsibilities while Aviva launches the hunt for a new chief executive.

He will chair a committee of three executive directors – UK insurance chief executive Andy Briggs, chief financial officer Thomas Stoddard, and international insurance chief executive Maurice Tulloch.

The move follows Mr Wilson's decision in March to join the board of rival asset manager BlackRock, which angered some shareholders.

FTSE 100 firm Aviva said it was time for 'new leadership' after five years under Mr Wilson in which he led a turnaround which the company said was now complete.

'He leaves the group in a far stronger state than when he joined,' said Sir Adrian. 'Aviva is now financially strong and delivering solid earnings growth.

'There is much further to go in accelerating our strategic development and enhancing shareholder value. We have agreed with Mark this is the right time for a new leader to ensure Aviva delivers to its full potential.'

Aviva will commence the search for a successor immediately. The process is expected to take four months.

Mr Wilson said: 'When I joined Aviva, the company was in poor health. Aviva is very different today.

'I have achieved what I wanted to achieve and now it's time for me to move on to new things.

'It has been an honour to lead Aviva through this period of immense change. I am happy I leave the company in a strong position from which it can thrive.'