Classmates of the infected pupil will be given chest x-rays

The student, who has not been named, is a sixth form pupil at Clitheroe Royal Grammar School.

The infected pupil was diagnosed just before Christmas and is being treated with a course of antibiotics.

Those in the same classes as the pupil will have chest x-rays to ensure the disease has not been passed on. All 600 sixth form pupils will have skin tests.

Dr John Astbury, consultant in health protection for the Health Protection Agency North West, said: "There was one case of TB in the sixth form at Clitheroe Royal Grammar School.

"We have to wait six weeks after diagnosis before carrying out screening and that will be going ahead this week."

The symptoms of TB can include a cough that will not go away, feeling tired, weight loss, loss of appetite, fever, night sweats and coughing up blood.