(AFP) A thick haze caused by fires in Indonesia forced the cancellation of MAS internal flights in Sarawak for a third day today, airline officials said.

National carrier Malaysia Airlines (MAS) cancelled 22 flights by small aircraft today, up from 17 yesterday and two on Wednesday, as the air quality deteriorated, an airline spokesman said.

"All the flights had to be cancelled due to the haze which is getting worse compared to yesterday," he told AFP .

"This situation is beyond us. When it improves we will resume our flights in Sarawak," he added.

The spokesperson added air routes connecting the Malaysian peninsula to Sarawak were unaffected as they were serviced by bigger aircraft, which were able to fly in hazy conditions.

Smaller aircraft, which service the state's rural areas, have to fly at low altitudes and were therefore more affected by the haze, added Abdul Halim Othman, an official at Sarawak's Miri Airport.

The hazy skies follow the end of the rainy season and an increase in fires in the Indonesian regions of Kalimantan on Borneo and Sumatra, which are attributed to both deliberate land clearance and accidental outbreaks.

Hot spots

In 1997 and 1998 choking haze caused by forest fires in Indonesia enveloped the region, causing serious health and traffic hazards and disrupting airline schedules.

The department of environment also reported today that satellite images detected 121 hotspots -- areas showing high levels of heat caused by burning -- in Kalimantan.

"The haze this time is caused by a lot of burning detected in West Kalimantan," the department spokeswoman told AFP .

Seven stations in Sarawak reportedly had moderate Air Pollutant Index (API) readings while two -- Sri Aman and Kapit in southern Sarawak near the Kalimantan border -- were considered unhealthy.

"It's too soon to tell if the haze will improve, but readings seem to indicate that it's getting better," she said, adding that Sarawak was not expected to get much rain next week.

A spokesman from Sarawak's environment department said air quality had deteriorated at most of the 10 surveillance stations.

"Even though most areas are still within the moderate range, their readings have gone up since yesterday," he said.