The Health Protection Agency has confirmed four youngsters between the ages of two and 10 from the Reedley and Brierfield areas had contracted the bug, which causes sickness and diarrhoea, and are now recovering at home.

Three of the children had recently travelled to a part of Asia that has comparatively high rates of the infection and the fourth is a relative of the other three.

As a precautionary measure, members of their families and other close contacts including children in the Reception Year and Year 3 at the school have been vaccinated against the infection.

Dr Sohail Ashraf, from the HPA's Cumbria and Lancashire Health Protection Unit, said: "We have taken measures to limit the spread of infection, including vaccinating household contacts and classmates of the children.

"Hepatitis A is a viral infection that can cause nausea and vomiting, abdominal pain, diarrhoea, fever, tiredness, loss of appetite, jaundice and listlessness.

"It's an infectious illness that can spread from person to person.

"Three of the infected children had recently been abroad. Anyone planning an overseas trip, and particularly to a country outside Europe, should consult their GP surgery about travel vaccines, including Hepatitis A vaccine, at least two weeks before setting off."

Mrs Ruth Thompson, headteacher at Reedley Primary School, said: "We are working closely with the Health Protection Agency and following their advice on the precautionary measures we need to take."

Parent Miss Sharon Moore (39), of Amersham Grove, Burnley, said she had decided to keep her two sons off school for the last few days of term as a precaution as they were not in the classes being vaccinated.

"I think they should have closed the school because of this."