Online penetration of Britain's grocery market will double again in the next few years, the boss of online supermarket Ocado forecast on Tuesday.

Industry data shows penetration has almost doubled in recent months to 13% from 7% before the COVID-19 pandemic hit.

"We strongly believe that demand will continue to grow. I think we'll see another doubling of the (online grocery) market in the next few years," Ocado Chief Executive Tim Steiner told reporters after the firm published first half results.

He said once levels of 20-30% were reached the economics of stores would be challenged. "You'll then see a continued channel shift to significantly greater market share and ultimately to be the mainstream market share."

(Reporting by James Davey; Editing by Alistair Smout)