Associated Press, Jakarta – Worried about a constant smoke haze hanging over his country and its neighbours, President Suharto yesterday imposed an immediate ban on lighting fires to clear forest land.

Environment Minister Sarwono Kusumaatmadja said Mr Suharto had ordered plantation companies to stop all land clearing.

"If they disobey, serious punishment will be imposed," he said after a meeting with Mr Suharto. He did not elaborate on possible penalties.

He said about 300,000 hectares of forest had been burned in drought-stricken Kalimantan and Sumatra since May.

Hundreds of fires have caused a thick pall over many parts of Indonesia and neighbouring Malaysia and Singapore.

At least three airports in Indonesia have been shut down since the weekend because of poor visibility, and cars have been forced to drive with lights on during daytime in some areas.

The smoke has worsened already chronic air pollution over Jakarta and a thick haze has covered Malaysia's capital, Kuala Lumpur, while Singapore's Environment Ministry has received dozens of complaints about air pollution daily.

Mr Sarwono estimated last week that as many as 20 million people could suffer respiratory, eye and other health problems from the smoke.

"The President considers the forest fires as very serious. They have to be stopped immediately by any means," he said yesterday.

He said most fires had been deliberately lit by plantation companies wanting more land for cultivation, and rejected claims that slash-and-burn farming by indigenous people was the main cause. Mr Sarwono said about 40 plantation companies had agreed to adhere to the fire ban.

Malaysia and Singapore had provided information from satellites to help track the progress of fires, he said.

Malaysia has also started a cloud-seeding programme to trigger rainfall to clear the air, and Mr Sarwono said Indonesia would begin a similar project.

Officials have said the fires will continue to burn until the monsoon rains, but meteorologists predict the rains may be delayed by months because of the El Nino weather phenomenon over the Pacific Ocean.