Record smog in Singapore has prompted emergency talks with Indonesia on how to extinguish fires on the island of Sumatra. Smoke plumes drifting across the sea have also forced school closures in Malaysia.
Indonesian President Susilo Bambang Yudhoyono ordered a mobilization of "all the country's resources" on Friday to extinguish peat and land-clearance fires on Sumatra, which lies west of Singapore.
Singapore's pollution standards index (PSI) soared to 400 on Friday, exceeding levels recorded during the smog disaster that gripped Southeast Asia in 1997 and disrupted shipping and air travel.
"No country or corporation has the right to pollute the air at the expense of Singaporeans' health and wellbeing," said Balakrishnan.
Singapore has a reputation for cleanliness. The severe deterioration of air quality began on Monday.
Artificial rain bid
Indonesia's disaster agency said it had sent two helicopters with cloud-seeding equipment in the hope of triggering rainfalls over Riau province, where hundreds of hectares of peat land are ablaze. The central Sumatran province lies opposite Singapore across the Strait of Malacca.
Stores in Singapore were reportedly close to running out of face masks used by commuters. The city-state has suspended military field training. Deliveries by fast-food firms and several sports events, including sailing contents, have been halted.
Prime Minister Lee Hsien Loong advised residents to stay indoors as much as possible, warning that the haze could persist for days.
"It can easily last for several weeks and quite possibly longer until the dry season ends in Sumatra," Lee told a press conference.
Coughs and low visibility
General practitioner Philip Koh said 80 percent of patients he had examined were suffering from smog-related ailments. Many complained of coughs.
At Singapore's aviation hub, Changi Airport, flight controllers were told to take extra precautions because of the low visibility.
The investment bank Barclays Plc said Singapore's key tourism sector would suffer "an immediate hit."
In areas of Malaysia, neighboring Singapore, 200 schools were told to stay shut until Friday at least.
Illegal burning on Indonesia's Sumatra island to clear space for palm oil plantations is a chronic problem during the June to September dry season.
Laksono told reporters on Thursday that the Indonesian government was investigating whether large companies were behind the fires.
"If there are, some are owned by Indonesians, Malaysians, Singaporeans," he said. "We will take action if they are found responsible. But there must be a process."
Indonesia's Forestry Minister, Zulkifli Hasan, said there were more than 100 hotspots - 80 percent of them on agricultural and plantation land and the rest in forests.
ipj/jr (AP, Reuters, AFP)