Faecal bacteria has been found on ice used by three of the UK's biggest coffee chains, according to an investigation.

Samples of iced drinks from Costa Coffee, Starbucks and Caffee Nero were found to be contaminated with the bacteria in lab tests carried out by BBC One consumer series Watchdog.

Seven out of 10 samples of Costa ice were said to be contaminated with bacteria found in faeces, known as faecal coliforms.

At both Starbucks and Caffe Nero, three out of 10 samples tested contained the bacteria.

Expert Tony Lewis, of the Chartered Institute of Environmental Health, described the levels found as "concerning".

"The bacteria found are opportunistic pathogens – the source of human disease. These should not be present at any level, never mind the significant numbers found."

Cleanliness of tables, trays, and high chairs at the chains was also tested at 30 branches.

Ice used by Caffe Nero, Costa and Starbucks was found by the BBC to be contaminated Getty

All three companies said they had now taken action. Costa said it had updated its ice-handling guidelines and was in the process of introducing new ice storage equipment.

Starbucks said it took hygiene "extremely seriously" and is now conducting its own investigation into the claims.

Similarly, a Caffe Nero spokesman said "a thorough investigation" was underway, and that the chain would take "appropriate action".

Last year another BBC One consumer show, Rip Off Britain, reported that faecal bacteria had been found in the ice served at a Birmingham outlet of KFC.

The fast food chain said at the time it was "extremely disappointed" by the results and had "immediately launched an investigation".

The Watchdog programme will air on BBC One on Wednesday at 8pm.