WM Morrison is likely to have to spend around 50% more to convert the stores it bought from Safeway for £3bn earlier this year.

Since July this year the grocer has been converting three Safeway stores a week, and it plans to continue at this pace for the next two years with completion scheduled for November 2006. There should be 53 shops trading therefore by this Christmas.

The stores are now expected to cost more than expected to revamp, due to previous neglect. This means the cost of changing each store to the Morrison fascia will now total around £1.5m, which is £500,000 more than planned.

The news comes after Morrison issued its first profit warning in its history this July, but the company has said the expenditure programme for converting Safeway stores would not exceed the £525m budget in the current financial year, according to newspaper reports.