The Asian Games could be threatened if forest and plantation fires are not addressed early, an Indonesian disaster management agency official has been quoted as saying.

The Games taking place between Aug 18 and Sept 2 are, for the first time, being co-hosted by two Indonesian cities - Jakarta, the capital, and Palembang, in Sumatra.

The Sumatra-based official warned that fires, if not addressed early, could spread and become difficult to control, nationwide television station Indosiar, reported.

Mr Edwar Sanger, head of Riau's disaster management agency, was speaking on Wednesday after news broke that four provinces - Riau, South Sumatra, West Kalimantan and Central Kalimantan - were on disaster alert because of a rising number of hot spots within their boundaries.

"With the disaster alert being declared, we could better coordinate work with the military, police, local governments and seek help. I will report immediately to headquarters to send in helicopters for water bombing and aircraft for cloud-seeding," he told Indosiar.

Dr Sutopo Purwo Nugroho, the spokesman for BNPB, the national disaster management agency, disclosed the alert status, which means that the government in Jakarta will now be able to intervene easily and with less red tape to deal with the fires, including deploying troops and providing logistics and funds.

Yesterday, there were a total of 15 hot spots across the country, with only two recorded on Sumatra. Nine were in Kalimantan in Borneo and the remaining four on Java island. The figures represent a sharp drop from the day before when 78 hotspots were recorded throughout the archipelago.

The hotspots on Wednesday in Riau province - which is close to Singapore - were located in Indragiri Hilir, Bengkalis and Pelalawan. More than 500ha were affected and some residents exposed to choking haze, Indosiar, citing Mr Edwar, reported.

Pekanbaru, Riau's capital, however has so far been spared.

Mr Patrick Tampubolon, an information officer at the Sultan Syarif Kasim II International Airport in the provincial capital, said that visibility was recorded at 10km at 1pm, well above the distance required for any plane to take off or land.

"Tuesday morning, we had rain that lasted a short while, and in the evening more rain fell for longer," Mr Patrick told The Straits Times. "In the past week, we saw a total of three days of rain".

The peatlands of Riau province are by far the most extensive in Sumatra, accounting for more than 50 per cent of the total on the island. The fragile, flammable peatlands are a major source of the choking annual haze that has blighted the region in the last two decades.

In 2015, six of the 14 districts and cities in Riau recorded hazardous PSI levels for extended periods. Malaysia and Singapore also suffered as a result of the raging forest and plantation fires in Indonesia.

Indonesian provinces near the equator are now in their first phase of the dry season, which usually runs from early in the year to March. The rainy season then sets in until May, before a more intense dry season from June to September.

Singapore's National Environment Agency on Wednesday said the likelihood of transboundary haze affecting Singapore was assessed to be low.