(Changes dateline, recasts with Indonesian jet skidding) JAKARTA, Oct 3 (Reuters) - A passenger jet skidded off the runway upon landing in thick haze in Indonesia on Tuesday as forest fires in the country spread a pall of smoke around the region. A Boeing 737-200 jetliner skidded 50 metres (164 ft) off the runway in the town of Tarakan in Indonesia's East Kalimantan province on Borneo island. "The visibility for the pilot was clouded by the haze," an airport official told Reuters, adding all 110 passengers of the Mandala airline plane survived the incident without major injuries. The haze, caused mostly by farmers and plantation owners setting fires to clear land, has forced many flights to be delayed or cancelled in Indonesia in recent days, with five cancellations in the Sumatra island province of Jambi on Tuesday. "The visibility is 500 metres," said Olan Simanjuntak, a spokesman for Sultan Thaha airport in Jambi. "We are very irritated (by the haze). Officials here are using masks." Purwasto, a senior official in Indonesia's Environment Ministry, told Reuters that the PSI reading was "more than 100" in the worst-hit parts of the country. "It is dangerous for human health," said Purwasto, who like many Indonesians uses one name. SMOKY SINGAPORE South-southwesterly winds have blown smoke from fires in central and south Sumatra to Singapore and Malaysia, obscuring sunlight and reducing temperatures and visibility. Singapore's Pollutants Standards Index (PSI) was at the highest level this year, the National Environment Agency (NEA) said on Tuesday. The NEA said said on its Web site (http://app.nea.gov.sg/psi/) that Singapore' PSI level reached 73 on Monday, although rain could bring some relief. A PSI reading between zero and 50 is considered "healthy", 51-100 "moderate" and 101-200 "unhealthy". Each year, uncontrolled slash-and-burn practices by farmers, plantation owners and loggers on the Indonesian islands send a smoky haze to Singapore, Malaysia and southern Thailand. "Villagers open land by burning. They consider that after burning, the land will be fertile," said Parigan Syahrin, head of the mines, energy and environment office in Banyuasin regency in South Sumatra. The NEA said satellite pictures showed 97 hotspots and dense smoke haze in Sumatra, a large Indonesian island west of Singapore. "The current dry weather conditions in southern parts of Sumatra are expected to persist until mid-October," the NEA said. The haze has also begun to envelop Malaysia's capital Kuala Lumpur, obscuring hills surrounding the city. But residents said it was nowhere near as bad as last year's choking smog. The Malaysian states of Sarawak and Sabah on Borneo were the worst affected on Tuesday. In one area of Sarawak, which has been blanketed by heavy smog for weeks, the air-pollution index approached "very unhealthy" levels at the daily 0300 GMT reading. Local media said authorities plan to seed clouds over Sarawak in an effort to clear the haze, but have not said when the operations will begin.
