Greensward College in Hockley has 1,600 pupils but since 12 January, 1,267 pupils have been off with winter sickness virus.

Parents have been informed of plans to close the school for 11 to 18-year-olds this Friday to disinfect the premises.

The school's head teacher Debbie Stokes said all necessary precautions had been taken to contain the infection.

Premises disinfected

"The school was thoroughly disinfected last weekend; central heating systems were turned off to cool the premises down and windows and doors opened, but it doesn't seem to have worked," she added.

Mrs Stokes said pupils who have shown symptoms have been sent home and advised not to return for 48-hours.

A spokesman for Essex Health Protection Unit said: "The virus is very infectious, but people do get well very quickly."

School governors decided the school should be closed on Friday because of the high level of sickness among both pupils and staff.

The premises will be disinfected again on Friday, Saturday and Sunday and the school is expected to reopen on Monday.