Shes landed on Monday and gone straight into work on Wednesday, where there are very young children, despite potentially incubating the virus.

What if she suddenly came down with it and started coughing and sneezing in front of the kids?

Parents were yesterday told there was no risk of an outbreak as the teacher did not display symptoms before voluntarily going home.

The Health Protection Agency said it understood parents concern but insisted they had nothing to fear.

A spokesman said: It has been confirmed to parents that a member of staff had been in contact with confirmed cases of swine flu.

We want to reassure parents that a this moment the person is not ill or displaying any symptoms. She has been given anti-viral medication as a precaution.

As the person displayed no symptoms when at the nursery, there is no need for any action to be taken.

The school declined to comment.

However, bosses have sent correspondence home to parents which said: Our member of staff was not, and is not, exhibiting any symptoms and is therefore not contagious.

As an extra precaution, she is not returning to pre-school until the maximum incubation period has passed.