Malaysians were urged Tuesday to stay indoors and take precautions as haze reached unhealthy levels in the capital and outlying states.
"As the haze is back, keep yourself properly hydrated, stay indoors if possible and avoid strenuous outdoor activities," Prime Minister Najib Razak tweeted.
Natural Resources and Environment Minister G Palanivel said the pollution was caused by fires in Indonesia's island of Sumatra.
He said the Asean Specialised Meteorological Centre reported 116 hotspots in Sumatra over the weekend.
Smoke from land-clearing fires in Sumatra is a perennial problem afflicting the South-East Asian nations of Malaysia, Singapore and Indonesia during the dry season.