The government today banned open burning after a week of thick haze which has choked the capital Kuala Lumpur and surrounding areas.

"Open burning has been banned in all areas in Selangor, Kuala Lumpur and Putrajaya, except for cremations, religious rites and barbeques," the Natural Resources and Environment Ministry said in a statement.

Offenders could be fined up to RM500,000 or jailed for not more than five years or both.

Kuala Lumpur and five areas including the country's administrative centre Putrajaya remained officially "unhealthy", as was Tanjung Malim in Perak.

Visibility was one kilometre at the Kuala Lumpur International Airport, the meteorological services department said.

The capital's suburbs of Subang and Petaling Jaya were also experiencing reduced visibility of around 0.8 km.

According to the Star daily, visibility on a major highway linking southern Negeri Sembilan state to the Kuala Lumpur suburb of Shah Alam and KLIA had dropped to between 0.5 kilometres and 0.2 kilometres.

Normal visibility in Malaysia is over 10 kilometres.

Release readings

Malaysians were advised Monday to wear masks outdoors. Strenuous activity outside would be unhealthy for most people, especially for those with respiratory problems like asthma and allergies, authorities said.

In an editorial, the Sun newspaper described the haze as "the worst haze we have had since 1998" and criticised authorities for not releasing pollution readings.

"That policy, which shows contempt and disregard for the health and well-being of Malaysians, must be disregarded in the interest of greater transparency," it said.

In 1997, at the height of the regional haze crisis, Malaysia classified the air pollution index as an official secret.

Malaysia now only refers to air quality as "good, moderate, unhealthy or hazardous" after banning the release of air pollution figures for fear it might drive away tourists. Tourism is Malaysia's second largest foreign exchange earner.

Hundreds of blazes in Indonesia's Riau and North Sumatra provinces, along with several fires in Indonesia's Kalimantan and Malaysia's Sarawak and Sabah states on Borneo island are blamed for causing the haze.

Peat fires in Cyberjaya, south of Kuala Lumpur, last week, have also contributed to the smog in the capital, blocking out views of the city's skyscrapers and permeating buildings with the smell of smoke.

In 1997 and 1998 choking haze caused mainly by Indonesian forest fires enveloped parts of Southeast Asia including Malaysia for months, causing an estimated 9.3 billion dollars in economic losses to the region.