Ice from three of the UK's biggest coffee chains has been found to contain bacteria from faeces, according to a BBC investigation.
Samples of iced drinks from Costa Coffee, Starbucks and Caffe Nero contained varying levels of the bacteria, the BBC's Watchdog found.
Expert Tony Lewis said the levels found were "concerning".
"These should not be present at any level - never mind the significant numbers found," he added.
Cleanliness of tables, trays and high chairs at the chains was also tested at 30 branches.
Seven out of 10 samples of Costa ice were found to be contaminated with bacteria found in faeces.
At both Starbucks and Caffe Nero, three out of 10 samples tested contained the bacteria known as faecal coliforms.
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Mr Lewis, of the Chartered Institute of Environmental Health, said these kinds of bacteria were "opportunistic pathogens - the source of human disease".
Costa said it had updated its ice-handling guidelines and was in the process of introducing new ice equipment storage.
Starbucks said it was now conducting its own investigation into the claims.
A spokesman said the chain took hygiene "extremely seriously".
Similarly, a Caffe Nero spokesman said "a thorough investigation" was under way, and that the chain would take "appropriate action".
The Watchdog programme will air on BBC One on Wednesday at 20:00.