Bradford-based supermarket Morrisons blamed worsening trading on its weakness in convenience and online retailing as underlying sales slumped by 2.4 per cent in its latest quarter.

Britain's fourth-biggest grocer said subdued consumer confidence also hit sales, with supermarkets being forced into heavy discounting to win over cash-strapped shoppers.

The deterioration in like-for-like sales in the 13 weeks to the start of November was worse than expectations for a 1.7 per cent decline and will heap further pressure on chief executive Dalton Philips.

It follows a 1.6 per cent decline in the six months to the start of August, after industry figures showed the chain's market share has shrunk to around 11.2 per cent from 11.4 per cent a year ago.

Morrisons, which is pinning hopes on an expansion into online retailing and convenience stores, said its low exposure to these areas "continues to impact sales performance".

It said the market will remain "challenging" for the rest of the year, but insisted the performance was in line with its expectations.

Morrisons said it is on track to have 100 convenience stores by the year end and open another 100 in its next financial year. It is launching its online food offer in partnership with internet grocer Ocado in January.

Dalton Philips said: "We continue to grow our sales in this tough market whilst making great progress on our strategy to be a multi-channel retailer. I said at the outset that our online offer would be unmistakably Morrisons and I'm very confident that the service we unveil in January will live up to that promise."