The service allows members with debit cards to top-up their pay-as-you-go mobile phones at branch-based cash machines, although Nationwide says the service will also be available at a few off-site machines.

Customers with Virgin, Orange, O2, Vodafone, Tesco Mobile and T-Mobile phones can use the top-up service. Card-account customers of the Co-op Bank, Royal Bank of Scotland, NatWest, Lloyds TSB and Allied Irish Bank can also purchase airtime at the Nationwide ATMs.

Stuart Bernau, Nationwide's executive director, says: "With so many people using mobiles, we wanted to give consumers the opportunity to top up their phones 24 hours a day with no additional charge to that of the service provider."