Smoke haze from forest and ground fires in Indonesia's Sumatra island has spread to a coastal town in neighbouring Malaysia, the environment department said.

The air quality in one of the towns where a state of emergency was declared last month over the haze hit the unhealthy level after weeks of blue skies.

The air pollution index in Kuala Selangor, west of the capital Kuala Lumpur, rose to 104 Sunday, which is deemed unhealthy.

Nationwide, including in Sabah and Sarawak states on Borneo island, the air quality remained moderate.

Kuala Lumpur and the west coast, which is separated from Sumatra by the narrow Malacca Strait, bore the brunt of the haze crisis last month. But cloud-seeding to induce rain and the deployment of fire fighters to Indonesia help clear the smog-filled skies.

Hot spots

The environment department said satellite images provided by the Asean Specialised Meteorological Centre Saturday showed there were 78 "hot spots" in north Sumatra and 391 hot spots in Indonesia's Kalimantan on Borneo.

Hot spots were also detected over peninsula Malaysia and in Sabah and Sarawak states, it said.

The fires are lit by cultivators to clear land, causing serious health and environmental damage.

Indonesia's forestry ministry has said that eight out of 10 plantation firms accused of setting fires in Sumatra were Malaysian-owned.

The firms denied the claims and said smallholders on the fringes of their plantations were the culprits.

The haze last month smothered Kuala Lumpur and surrounding districts as well as the west coast, briefly shutting down the country's biggest port as pollution reached extremely hazardous levels. - AFP