A third of cash machines charge fees for withdrawing money, according to a Nationwide Building Society survey.
Nationwide said an increasing number of dispensers were charging for withdrawals and warned that, unless consumers become more aware, free machines could disappear.
Five years ago, scarcely any cash machines levied charges. But since then, the number of dispensers in the UK has risen from 28,000 to more than 50,000, with most of the new machines charging an average £1.50.
Most of the fee-charging machines are in convenience locations, such as corner-shops, garages and pubs.
Nationwide is calling for a code of practice, including prominent warnings on fee-charging machines as well as a cap on the level of charges.
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