Jakarta Globe – A heavy smoke haze from forest fires curbed visibility in Riau early on Friday, forcing delays in flights landing and taking off from the Pekanbaru airport, an official said.

"Visibility was very low this morning. It was still at just 300 meters at 7:00 am," said Farman, from the meteorology office in the Riau capital of Pekanbaru.

He said that strengthening winds, reaching up to 4 knots from the south, finally helped clear the sky and by 9:20 a.m. visibility had improved to some 1,000 meters.

"The bad visibility delayed at least two flights from the airport this morning," Farman said, adding that the flights – Mandala and Lion Air flights to Jakarta – had been each delayed two hours.

Farman said that the delays had become a daily routine in the past two weeks as the fires continue to rage.

"The haze is really thick in the morning and, depending on the winds, it has usually cleared up by around 10 to 11 in the morning," he said.

The haze often returned in the late afternoon and stayed thick until the following morning, he added.

The haze has been blamed on the practice of clearing land using fire for the upcoming planting seasons, coinciding with the beginning of the rainy season. Although the practice is outlawed, enforcement has been weak because of manpower and fund limitations.