THREE people, including a 75-year-old pensioner, were seriously ill in hospital last night after being struck down by the potentially fatal bug E.coli.

Castle Bank Butchers, in Front Street, Chester-le-Street, County Durham, which is at the centre of an investigation into the outbreak, has closed temporarily.

Health officials said there were nine confirmed cases and another five unconfirmed.

The three adults who are seriously ill in the University Hospital of North Durham were said to be comfortable last night. A child was also taken to hospital but has since been discharged.

The nine cases are from four households in the Durham and Chester-le-Street area. All are believed to have eaten cooked meat bought from Castle Bank.

Dr Deb Wilson, chairwoman of the Health Protection Agency's outbreak control team, said: "E.coli infection can, extremely rarely, cause death and the very young and old are always more susceptible.

"So far, we have identified one possible link to a particular food outlet in Chester-le-Street and cold, cooked meat products.

"No other outlets have as yet been identified."

She stressed that Castle Bank was as yet only a potential source of the outbreak.

Public health and environmental health officials from Chester-le-Street District Council, and Durham and Chester-le-Street Primary Care Trust are carrying out an inquiry, along with the Health Protection Agency.

"Investigations are continuing into the possible source of the infection and links between cases," said Dr Wilson.

"Further information is still awaited from local and national laboratories, which will allow us to more accurately determine if cases are truly linked."

The strain of the bug has been identified as E.coli 0157. Its effects range from diarrhoea to a severe illness that can lead to kidney damage.

Dr Wilson said: "The proprietor of Castle Bank Butchers is co-operating fully with Chester-le-Street District Council and has agreed to close voluntarily for a short period while investigations continue."

The public have been advised to throw out any cooked meats purchased from Castle Bank Butchers.

Dr Wilson admitted that the first E.coli case was confirmed last Monday.

But she disagreed that most people who had bought cooked meat early last week would have eaten it by now. "We cannot guarantee how long people keep cooked meat in their fridges," she said.

The investigation will last a minimum of several days, and could stretch into weeks.

The Castle Bank chain, operated by John Hall, also has outlets in Esh Winning, near Durham, Crook and Stanhope, plus a flagship shop, JD Hall's, in Corbridge, North-umberland. No other branches are under investigation.

E.coli 0157 can be found in the intestines of healthy animals, and meat or milk can become contaminated during slaughter or milking.

The worst outbreak of E.coli - in Wishaw, Scotland, in 1996 - centred on a butcher's. Twenty-one people died.

Anyone who develops severe diarrhoea or is concerned they have contracted the bug should contact their GP, or ring NHS Direct on 0845 4647.

Mr Hall was unavailable for comment last night