Parklands High School told parents that the closure is needed to "protect the rest of the students and staff" after a significant number of pupils tested positive in recent days.
In a message to parents yesterday afternoon (Tuesday, June 15), headteacher Steve Mitchell said the school will stay closed until Monday, June 21 and will undergo a deep clean.
He said: "The governing body and I have taken the difficult decision to close school for the remainder of the week, in order to have a deep clean of the school.
"This is due to the number of positive cases we are currently experiencing. School will reopen on Monday, June 21.
"Unfortunately, the number of cases we have is unsustainable. We feel that this is a suitable intervention at this present time to try and protect the rest of the students and staff.
"The school has been in contact with the Lancashire County Council Public Health Team who have agreed with our course of action.
"We will move to blended learning for ALL students. We fully understand that this is far from ideal, but we have consistently followed the guidance from the Department of Education and Lancashire County Council."
Mr Mitchell added that a "large number" of those pupils with Covid had not been tested at home as instructed, and this had contributed to a school-wide outbreak.
He said: "We have had a large number of positive cases where the child has told us that they have not been taking the tests at home.
"This has resulted in asymptomatic pupils being in school and infecting others, who then go to develop symptoms.
"This means we have had to identify a very large number of close contacts, who have had to self-isolate.
"I cannot stress enough how important it is that your child takes twice weekly lateral flow tests."
The school said it has provided all students with a PCR test for pupils to take on Sunday, June 20 before returning to class.
Parklands did not reply to a request for comment and Lancashire County Council said it was unable to comment due to the school having academy status.
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