KUALA LUMPUR -- Malaysia will try to make rain by seeding clouds and prepare to shut schools as the quality of air in various places deteriorates, the Department of Environment said, raising fears of a new round of pollution from forest fires.

Almost every dry season, smoke from fires to clear land for palm oil and pulp and paper plantations in Indonesia clouds the skies over much of the region, bringing risks to public health and worrying tourist operators and airlines.

Malaysia's air quality was deteriorating, particularly in the western part of Peninsular Malaysia, with 11 areas recording unhealthy air pollution index (API) readings, the department's director general, Wan Abdul Latiff Wan Jaffar, said in a statement late on Monday.

Malaysia said last week fires in neighbouring Indonesia were causing the pollution although Indonesia has denied detecting any smoke drifting over its borders into Malaysia.

The Malaysian department said earlier on Monday a regional meteorological agency had detected nearly 250 "hotspots", indicating fires, on Indonesia's Sumatra island and in its part of Borneo island, with none in Malaysia.

Efforts to clear the air with rain by seeding clouds and other measures to cope with the pollution would come into effect when API readings reached 150 for more than 24 hours, Wan Abdul Latiff.

Schools and kindergartens must stop all outdoor activities when API readings reach 100, and close when they reach 200, he said.

The environmental group Greenpeace, meanwhile, called on countries in the region to introduce legislation to stop plantation companies causing air pollution.

"Enacting a domestic transboundary haze act is necessary to act as a deterrent, especially as there are bad apples in the industry," Heng Kiah Chun, regional campaign strategist for Greenpeace Southeast Asia, said in a statement.

Singapore, which prides itself on its clean air, passed a cross-border air pollution law in 2014 that makes those who cause haze both criminally and civilly liable.