BBC Environment Correspondent Margaret Gilmore: 'The dairy industry will feel this'

A wider survey is now being carried out into initial findings that a bug linked to bowel disease can be found in up to a fifth of pasteurised supplies.

Experts from the Ministry of Agriculture, Fisheries and Food (MAFF) will spend 18 months investigating at least 1,000 samples of all types of milk for the bacteria mycobacterium paratuberculosis.

Tesco suppliers will treat milk for longer

The bacteria causes Johne's disease, a disorder in cattle across the world.

But it is one of several factors that have been suggested as causing Crohn's disease, a chronic intestine inflammation which can in some cases lead to tumours.

Food Safety Minister, Jeff Rooker, has said the government had to release the information.

The National Dairy Council, the body which represents dairies and dairy farmers, has welcomed the decision to investigate any possible problems.

A spokeswoman for the council, now planning a campaign to promote milk, said: "We are very pleased they are going to investigate further and make sure this thing is killed stone dead.

"We don't want anything to taint the pure, natural image of milk."

Pasteurisation time increased

The industry has been acting to reassure customers as precautionary safety measures were introduced by dairies and supermarkets to maintain consumer confidence.

Tesco, the UK's largest supermarket chain, has instructed all its suppliers to increase the length of the pasteurisation treatment for any milk produced for its stores.

Normal production methods mean heating milk products to 72C for 15 seconds.

Tesco has increased the length of the process, used to kill bacteria in fresh milk, to 25 seconds at the same temperature.

Dairy Crest, one of UK's biggest milk producers, said it and other large dairies were "taking measures to review procedures" following the government announcement.

Further food crises predicted

Consumer bodies have predicted that the milk safety scare would be followed by further food crises unless the government introduced a proposed Food Standards Agency

The Consumers' Association has been lobbying ministers for five years to hasten plans for the new body.

Tim Bennett of the National Farmers Union: Public must make own decisions

Such an agency would deal with all food safety matters and provide information to the public, as well as coming up with solutions to problems such as the milk scare.

The agency has still not materialised, despite backing from Mr Rooker, according to the Consumers' Association.

A spokeswoman for the association said the government should not be surprised if the public reacted negatively to assurances

She said: "They have released this information into the public arena. But now what? We can all go and panic about it?"

Government body needed

A campaign is to be launched to promote milk

The spokeswoman said the issue at the moment was the proposal for the FSA and urged the government to introduce a bill in the next session of parliament to establish the body.

She said: "Consumers and the industries involved are willing to take action but they need a government body to lead them.

"They need someone to set out guidelines and present solutions. Otherwise the consumer becomes the victim of half-hearted efforts to pacify them.