Tesco is to double the number of in-store telecoms shops in its supermarkets by the end of the year.

Tesco, which reveals its full-year results on Tuesday, is to open more than 100 shops selling mobile and landline packages in its largest stores by next March. It will also rebrand them as ‘Phone Shop’.

The move is part of Tesco’s strategy to expand beyond groceries and will put pressure on market leader Carphone Warehouse. Tesco will in particular seek to expand its contract phones business – it already has a 13 per cent share of the pay-as-you-go phone market in the UK.

Tesco is expected to record bumper £3.01bn profits tomorrow, with sales equivalent to £1bn going through its tills each week. It has suffered some market share dip though, attributed to aggressive discounting by rivals and the growth in discounters such as Aldi and Lidl.

Tesco is also expected to reveal it has begun testing its Clubcard loyalty programme in Poland, Slovakia, Turkey and Thailand.

Tesco UK marketing manager Carolyn Bradley told The Sunday Times: “We think that in this market loyalty is critical.” She added that Clubcard is “an incredibly powerful” tool to keep shoppers coming back.