Sir Ken Morrison has been under fire recently

The company said that Sir Ken would be stepping down as chairman, a role he has held since 1967, and as a director of the firm at the start of 2008.

The company is under pressure to recruit a new chief executive after its performance deteriorated in the wake of its 2004 takeover of Safeway.

Morrisons said it expected to fill the position within two to three weeks.

Calls for change

Sir Ken will take on the role of life president when he steps down in 18 months time.

In a trading update ahead of the company's Annual General Meeting, Morrisons said like-for-like sales rose 6% in the 16 weeks to 21 May.

We now have a solid base for the future Morrisons Check Morrisons' share price

Morrisons has issued a series of profit warnings in the past 18 months, as problems with integrating the Safeway stores it acquired have dogged the business.

This has led many investors to call for a change of leadership at the company.

Morrisons said its share of the grocery market had stabilised after its recent problems and that it was now anticipating future growth.