Schools have been ordered to close in the capital of Indonesia's Central Kalimantan province because of persistent choking haze caused by fires, an official said.

Palangkaraya mayor Salundik Goyong Wednesday ordered the closure with immediate effect of all schools in the city and surrounding areas, mayoral spokesman Halis Lanca said Thursday. "The closure will be until further notice is issued," he said.

He said closure was ordered because of the health hazard caused by the thick haze that has blanketed the area for weeks.

Early Thursday the haze, caused by smoke from burning forests and peat, had reduced visibility in the capital to around 10 meters. But visibility should slowly improve to just over 100 meters later in the day, said Indra Sarwono of the local meteorology office.

The provincial government has already given schools in the province permission to decide whether to close because of the haze, spokesman Harun al-Rasyid told AFP.

"Government employees who have difficulties working in the haze conditions are also allowed not to work although all basic public services have to remain functioning," al-Rasyid said.

The government last month set up a team of some 370 men, including forest rangers, police and soldiers, to try to put out the fires, he said. "But the problems they face are not easy." He said most of the fires were ground fires and they were difficult to extinguish because of the deep peat soil layers prevalent in the area as well as in large parts of Borneo island.

"These peat soil fires can only be extinguished by a large amount of water, such as continuous rains. Rains remain our main hope," he said. Access to forest areas that were on fire was also difficult because of the lush vegetation, al-Rasyid said.

The Palangkaraya meteorology office has forecast rains only sometime next month.

In Pontianak, the capital of West Kalimantan province also affected by haze, the sky was clear and visibility was over 3,000 meters by mid-morning as rains had fallen over the city the previous evening.

"It is clear now, but the sky may get covered again in the afternoon with haze carried by winds from the Ketapang [district] area where rains have not yet fallen," said Suwardi of the local meteorology office.

Haze has also begun to cover parts of Sumatra island.

In Pekanbaru, the capital of Riau province, the smoke from forest fires in the region was forced downwards because of a weather depression in the neighbouring province of West Sumatra and a tropical cyclone in the South China Sea in the east, meteorology official Slamet Riyadi said.

"The first two GMT hours, or seven to eight in the morning here, visibility was about 300 to 400 meters only because the smoke hung low," Riyadi said.

A slight rain helped improve the visibility to 500 meters an hour later, he said. "This condition, due to the depression and the cyclone, is expected to remain until at least tomorrow," he said.

Illegal loggers and farmers are blamed for the fires which they light to clear their fields for the next planting season. The fires have prompted neighboring Malaysia, Thailand and Singapore to call for action to contrl the haze.

The burning has caused smoke haze over the region almost annually since 1997.