The Selangor Education Department has ordered all the 131 schools in the Klang district to close Friday due to the haze.

On Thursday evening, the Air Pollutant Index (API) reached 233 in the 'very unhealthy' range.

Selangor Education Director Datuk Mahmud Karim said the instruction to close the schools was issued to the Klang District Education Office, Thursday.

He said the duration of the closure would depend on the haze and that an announcement would be made on the reopening of these schools.

The Department of Environment reported on its website that the haze was caused by the current drought and the rising number of cases of open burning.