Environment ministers from Southeast Asian nations afflicted by an acrid haze from land-clearing fires are to meet this week in Indonesia, the president's spokesman said today.

Malaysia and Singapore have been angered by the haze from fires raging in Sumatra and Kalimantan in Indonesia, which every year drift over parts of the region, causing health problems and disrupting travel and tourism.

Indonesian President Susilo Bambang Yudhoyono, who apologised yesterday to the two nations over the crisis, telephoned Singapore's prime minister to tell him the meeting was set for Friday in Pekanbaru, his spokesman said.

The city is the capital of Riau province on Sumatra island, near Singapore, and has been badly affected by this year's smoke.

Environment ministers from Brunei, Indonesia, Malaysia, Singapore and Thailand are to attend, a statement from the foreign affairs ministry said.

"The president puts high hopes on the results of the Asean ministerial meeting," Yudhoyono's spokesman Dino Patti Djalal said, referring to the 10-member Association of Southeast Asian Nations.

He said the president and Prime Minister Lee Hsien Loong, who wrote to Yudhoyono on Wednesday complaining of the haze, had discussed "ways to handle it".

"The president, once again, apologised for the inconvenience felt by Singapore and our neighbour Malaysia," Djalal said.

Jakarta to ratify treaty

The spokesman said Indonesia would ratify an Asean treaty on transboundary haze it signed in 2002, although he did not say when.

Parties to the treaty agree to act to prevent and control burning that may cause pollution in neighbouring countries.

Farmers continue to light fires every year to clear land ahead of the rainy season, even though the practice has been outlawed, and Indonesian authorities' enforcement of the law remains weak.

Singapore's environment agency was forced to issued a health advisory because of the fog-like haze last weekend, while this week Malaysia issued a hazard warning for ships in the Malacca Straits after visibility dropped dangerously along the vital waterway.