Singapore (ANTARA News) - Haze and acrid air from land-clearing fires in Indonesia's South Sumatra worsened Friday in Singapore, with conditions likely to persist for the next few days, meteorologists said.

The Pollutants Standards Index (PSI) hit 66, the highest this year, in the moderate range, after staying in the good range of 50 or below for most of 2006. A PSI reading over 101 is considered unhealthy.

Polyclinics reported seeing more patients with asthma and treating an increasing number for upper respiratory tract infections.

The National Environment Agency (NEA) said that the number of fires in South Sumatra has increased. Satellite pictures showed 178 hotspots, up from nine in a 24-hour period.

The south-southeasterly winds are not expected to change direction soon, said the NEA as reported by DPA.

Several people called The Straits Times complaining that the smell of smoke in the air had become unbearable.

Visibility has been considerably reduced for motorists.