Mismanagement of land
One environment campaigner told Al Jazeera on Saturday that "serious action" needs to be taken before billions of dollars worth of damage is caused.
Faizal Parish, director of the Malaysia-based Global Environment Centre, said: "We have a phenomenon called the El Nino effect which occurs roughly every seven years.
"This leads to very long droughts that can last up to six or even nine months. [However] El Nino just gives the dry conditions. The root causes of the fires are 100 per cent due to human activity - mismanagement of land."
Parish said fire prevention efforts need to be tripled.
"If we do not take serious action now, we will be in a situation like in 1997-98 when we had massive clouds of smoke that caused an estimated $10bn worth of damage.
"Although times may be hard, there needs to be rapid investment to prevent fires through better management.
"Particularly in peat areas which can burn for up to six months, where 90 per cent of the smoke haze is coming from," he said.
An Indonesian official said 47 hotspots had been recorded in Riau province in Sumatra by Thursday and temperatures were abnormally high at 35C.
In Malaysia, the haze had reduced visibility to in some areas surrounding Kuala Lumpur, the capital.
"We are monitoring the situation. We will decide later if any action should be taken," Rosnani Ibrahim, the department of the environment's director-general, said.
The ministry said it was working with police and private airlines to detect blazes through aerial surveillance.
Indonesia said it lacks the money and technical expertise to control the fires in the vast archipelago nation.