Forest fires in Malaysia enveloped the capital in a smoky haze as visibility at the Kuala Lumpur International Airport dropped to two kilometres, officials said today.

Some 160 firemen were working to control peat fires which have been raging since earlier this month, covering 57 hectares in Selangor which surrounds the capital, a district Fire and Rescue Department spokesman told AFP .

Fires in the wake of prolonged hot, dry weather have also caused pollution and reduced visibility in several other states, officials said.

Visibility was down to three kilometres in Malacca, the Meteorological Service Department's official website said.

Alor Setar, the capital of Kedah, recorded visibility of just 0.3 kilometres earlier on Wednesday before it improved to more than 10 kilometres.

The air quality deteriorated to "unhealthy" in four areas - Bukit Rambai located in southern Malacca, Seremban and Nilai in Negeri Sembilan, and in Shah Alam, Selangor, according to a statement from the Department of Environment.