The contamination is likely to have occurred because the ice, or ice making machines, has been touched by staff who have not washed their hands thoroughly after going to the toilet.
The coliforms were found at seven of the 10 samples taken from KFC, six of those from Burger King and three from McDonald's, the Daily Mail reported.
Four of the samples taken at Burger King and five at KFC were described as having "significant" levels of contamination.
Tony Lewis, the Head of Policy and Education at the Chartered Institute of Environmental Health, described the findings as 'extremely worrying'.
He said: "When we're finding the sorts of numbers we're finding here, you have to look at the people making the ice, handling the ice, which they then transfer into customers' drinks.
"And then you also have to look at hygiene failure with potentially the machines themselves: are they being kept clean?"
"We have strict procedures for the management and handling of ice, including daily and weekly inspections and cleaning of the ice machine and storage holds, as well as the routine testing of ice quality across our business.
"We immediately shut down the ice machines in the restaurants affected to conduct a thorough clean and inspection, and reinforced the importance of adhering to our strict procedures to all employees.
"The restaurants all have an Environmental Health Officer (EHO) hygiene rating of four or five out of five, and we are awaiting the results of independent testing of the ice that will confirm they are back up to the standards we expect.
"To reassure customers we have also inspected and cleaned the ice machines in all other restaurants across the UK."
Burger King said: "Cleanliness and hygiene are a top priority.
"The strict procedures we have in place are designed to ensure all Guests have a positive experience each time they visit our restaurants. We are proactively working with our franchisees in the UK to reinforce these procedures.
"This report is an opportunity for us to emphasise our training procedures and ensure all operations and safety standards are upheld."
McDonald's said: "We have robust procedures in place with regard to the production, storage and handling of ice in our UK restaurants.
"Nothing is more important than the safety of our customers and people and we will continue to review our procedures and training, working closely with our restaurant teams to ensure those procedures are adhered to at all times.
"Hygiene and safety practices are of the utmost importance to us and we're proud that 99per cent of our restaurants have an independent hygiene rating of either good or very good.
"Like many UK food retailers, our ice is made by freezing drinking water using commercial ice machines.
"As the investigation highlights, there are no specific ice production standards in place, only those relating to unfrozen drinking water. We would therefore welcome the introduction of an agreed standard and would be happy to work with relevant industry bodies."
