Around 60 Year One pupils at Sherwood Primary in Fulwood, Preston, along with six members of staff, were kept away from lessons while they were all tested for E.coli O157. This occurred after two pupils at the school were diagnosed with different strains of the bacterium.

A parent of one of the pupils has also tested positive for E.coli O157, along with a sibling who attends a different nursery school but was displaying no symptoms.

The pupils and staff were told to stay away until they had provided negative samples. No other children have tested positive so far.

Deep cleaning of classrooms, toilets, desks and chairs has taken place and equipment such as pencils, crayons and sand from the sandpit have been thrown away to prevent spread.

Mr Fann, head teacher at Sherwood Primary, said he hoped the two poorly pupils, who are recovering at home, would be fit to return after half-term.

Another case of E.coli has been reported elsewhere in the North West and the source of the infections is still being investigated

Dr Ken Lamden, a specialist with Cumbria and Lancashire Health Protection Unit, said: "This was a routine investigation of two cases of presumed E.coli O157 infection. There is no evidence of any spread of infection in the school, but to be absolutely sure, we asked for children in the same year to be kept at home until they provided negative samples. To date, all the samples we have tested have been negative and the children are returning to school."