Jakarta – Parts of Indonesia have been enveloped in one of the worst days of haze this year, officials said, as residents donned face masks to ward off thick, choking fumes.

The haze, caused by forest and ground fires across the country, descended on the province of South Kalimantan on Wednesday, reducing visibility and filling the air with noxious burning smells.

"We have had visibility problems because of the thick smoke since early in September, and today is one of the worst smoke attacks," a spokesman for the South Kalimantan airport in Banjarmasin said on Wednesday.

He said that no flights had been affected as the smoke had closed in after morning plane departures, but there had been 20 recorded disruptions to air traffic at the airport since September 1.

Mr Trija of the meteorology station in South Kalimantan said that visibility was reduced to 600m at one point. He said that face masks or wet scarves and handkerchiefs were being worn by people both outside and inside their houses.

Officials blame the haze on fires set by large forest and plantation concession holders, as well as by small farmers, to clear land for cultivation. The practice is illegal but officials find it difficult to enforce the law.

In 1997, and to a lesser extent in 1998, haze from forest fires in Indonesia enveloped parts of South-east Asia for months, causing serious health problems and traffic hazards.