Environment Minister Adenan Satem said the haze, which appeared last week, is concentrated over the Klang Valley site of Malaysia's main city, Kuala Lumpur, the administrative capital and a sprawling residential area.
"The situation is not getting better. It is getting worse," the minister said. He said he was going to Indonesia for talks with officials in hopes of finding a solution.
Flights at the Subang airport near Kuala Lumpur, used primarily by charter and private aircraft, were suspended after visibility plunged to less than 1,300 feet, said Daud Hosnan, senior operations manager for Malaysia Airports.
Visibility was better at Kuala Lumpur International Airport, and no flights were affected, Daud said. In downtown Kuala Lumpur, where the smoke even filtered into air-conditioned offices, nothing could be seen beyond 1,500 feet.
Northport, one of Malaysia's key western harbors facing the Malacca Strait, announced it was suspending operations until visibility improves.
The Meteorology Department said no respite was expected until October, when rains would help wash away the haze, a cocktail of dust, ash, sulfur dioxide and carbon dioxide.
An Environment Ministry statement said air quality in three places, including the Kuala Lumpur suburb Shah Alam, has become "hazardous." The air in the administrative capital, Putrajaya, and another Kuala Lumpur suburb, Petaling Jaya, was categorized as "very unhealthy."
Hospitals reported a spike in respiratory and eye ailments from the dust and smoke.
The Kuala Lumpur Education Department said schools would be closed Thursday and Friday because students were having breathing problems, the Star newspaper reported.
The haze compounded the stifling heat and humidity. People walked around Kuala Lumpur with masks over their noses and mouths, or used handkerchiefs to shield themselves from the acrid, throat-burning smoke.
The environment minister said an emergency would be declared if the air pollution index, which measures harmful particles in the air, rises above 500. In some places, the index already was 410.
It was the first time the government released air pollution index statistics in six years. It stopped revealing the index in 1999, saying the reports were scaring away tourists as they did in 1997 and 1998 when Malaysia was hard-hit by haze.
Officials blamed the haze on hundreds of fires in Indonesia. Some have been burning for more than a week.
But Gurmit Singh, who heads an environment watchdog group, questioned that claim, saying the haze could also come from unreported fires in Malaysia. He said the haze in Kuala Lumpur has the smell of smoke, indicating the source was nearby. "We make things worse by our vehicle emissions and the local fires," he said.