Singapore (AP) – Fires have broken out on the Indonesian island of Sumatra, where land-clearing blazes caused severe pollution in much of Southeast Asia in 1997, officials in Singapore said Thursday.

Such fires have become an annual problem during the region's mid-year dry season. The situation was disastrous in 1997, when thick haze spread to Singapore and parts of Malaysia.

"In the past few days, satellite pictures have shown intermittent hot spots in some parts of Sumatra," a Singapore government statement said. This year's fires are not now causing pollution in Singapore, it said.

The fires appeared to be near cultivated areas in central Sumatra, Singapore Meteorological Service spokesman Wong Teo Suan said. "I doubt it's really wild forest fires. It's probably some sort of human activity," he said.

Singapore monitors Indonesian forest fires by satellite as part of a regional cooperation program. "If the situation gets worse or spreads a little bit, we could get some slight incidence of haze" in Singapore during the monsoon rainy period in July and August, Wong said.

The haze was blamed for health problems and a drop in tourism in Singapore and Malaysia in 1997.