A BBC One television show will tonight examine hygiene practices at the top coffee and cafe outlets after revealing that seven out of 10 samples of Costa ice were found to be contaminated with bacteria known as faecal coliforms, and three in 10 samples at Starbucks and Caffe Nero were also affected.
The Watchdog programme, to be broadcast tonight, will investigate cleanliness at the brands' stores, with tables, chairs and trays also tested in the study.
Reported on BBC News today, expert Tony Lewis, of the Chartered Institute of Environmental Health, said that the bacteria "was the source of human disease", and "should not be present at any level - never mind the significant numbers found".
A spokesperson for Starbucks said the group took hygiene very seriously, and that it had launched its own investigation into the matter, while a Caffe Nero spokesperson said the chain would "take appropriate action".
Costa said its ice-handling guidelines had been updated and new ice equipment storage was in the process of being introduced.
The Watchdog show will appear on BBC One at 8pm tonight (Wednesday).