Much of peninsular Malaysia, including the capital, has been shrouded in thick smog for a week, presenting the country with its worst pollution crisis since 1997, when smoke mainly from Indonesian forest fires blocked out skies across Southeast Asia.

Malaysia sent its environment and commodities ministers on Thursday to the Sumatran city of Medan where they met Indonesia's forestry minister and officials from its Environment Ministry.

"I am going there to go on site and see what is happening," Plantation Industries and Commodities Minister Peter Chin said by phone before the meeting on Thursday.

Forest fires

Fires on the Indonesian island of Sumatra, which is a short ferry-ride away from peninsular Malaysia's west coast, flare up around this time every year as farmers, plantation owners and miners burn forests to clear land during the dry season.

The smog is caused by forest
fires on nearby Sumatra

Malaysia has offered to help Indonesia fight the fires, but Chin declined to say what it could realistically do to help to solve the problem or what he hoped to achieve from the Medan talks.

Malaysian companies own large tracts of oil-palm plantation in Sumatra. Asked if some of these might also be to blame for the fires, he added: "We will see what happens (during the visit)." In Indonesia, Malaysian-owned operations are often said to be behind the burning or to be turning a blind eye to it.

Haze from Indonesia has become an almost annual problem in Malaysia where it is often made worse by its own dry-season fires, but this time the smog has reached dangerous levels, according to health authorities.

State of emergency

Asthma attacks have soared and tourists are holing up in their hotels or seeking refuge in air-conditioned shopping malls at one of the busiest times for the country's tourism industry.

Schools in worst-affected areas are closed for the rest of the week, and a major port operator on the west coast suspended operations on Wednesday evening. An airport on the outskirts of Kuala Lumpur was closed on Wednesday for five hours.

A ship was reported to have run aground this week, and vessels plying the Strait of Malacca, one of the world's busiest sea lanes, are warned to take care because of poor visibility.

The government had said it would declare an emergency if the pollution index hit 500, a level considered hazardous. Kuala Lumpur registered 181 on Wednesday, with Putrajaya, the administrative capital, at 224, and Port Klang at 410.

Malaysia is starting to publish daily pollution measurements, reversing a 1997 decision to keep the figures secret, out of fears this would scare off tourism, a major industry generating 29.65 billion ringgit ($7.92 billion) in income last year.

The haze has hurt the local stock market, dragging down shares in the airport, airlines and tourism industries.