SINGAPORE (AP) _ Hazy smog from Indonesian forest fires hung thickly over Singapore all day today, causing the government to warn people away from rigorous outdoor activities.

Visibility was limited to about one mile, with skyscrapers on the Singapore skyline disappearing into the whitish-gray haze.

State-run television showed changing pollution levels in the corner of the screen during programs. The Pollution Standard Index _ developed by the U.S. Environmental Protection Agency to measure air pollutants _ registered 113 at 11 a.m., and rose through the day, hitting 169 by 5 p.m.

A level of 100 is considered unhealthy. Norman activities can cause skin and eye irritations, sneezing and coughing.

Hundreds of fires, many of them deliberately set to clear land for plantations, have been burning in forests and scrub lands across Indonesia for weeks, producing a thick haze that has drifted over neighboring Malaysia, Thailand, the Philippines, and Brunei as well as Singapore.

Health officials have linked the deaths of four Indonesians to smoke inhalation and thousands of people have fallen ill.

A late wind shift today saved Indonesia's capital, Jakarta, from the choking haze and rain began to cleanse skies over some other parts of that nation.

``The weather is starting to improve, but slowly,'' said weather forecaster Supardi.

Heavy rains had cleared skies in the northern sections of Sumatra, Borneo and New Guinea, he said.

A weather expert in neighboring Australia, however, predicted that lasting relief from the haze was still some way off.

``Logically, you wouldn't expect probably much (rain) until the end of October,'' Keith Coles of the Australian Bureau of Meteorology said in Canberra. ``It may even be delayed after that.''

Normally, heavy monsoon rains extinguish fires at this time of year. However, meteorologists say El Nino, an abnormal weather pattern over the Pacific Ocean, has triggered the worst drought in half a century.

Meanwhile, in Malaysia, a peat fire that raged for three days on the east coast state of Pahang was under control today and no longer a threat, news reports said.

Firefighters had to dig 6-foot ditches to halt the fire's spread because peat fires rage several feet into the ground, Pahang Fire and Rescue Services Director Amer Yusof said.

``The source of the fire has yet to be ascertained. It may be a cigarette butt, lightning or a burning pile of wood,'' said Amer. He said he did not believe the fire had been set to clear land.