The smog-addled city-state of Singapore got a breath of fresh air Monday when it woke up to blue skies, but neighboring Malaysia is still under a blanket of smoke caused by forest fires in Indonesia.

Slash-and-burn clearing of farm and forest along Indonesia's Sumatra island has sent a choking haze of smoke across the water to Singapore and Malaysia, causing the air pollution index in Singapore to reach record highs and prompting Malaysia to declare a state of emergency in two southern regions after the country's air pollution index exceeded 700. A reading of more than 300 is considered hazardous to human health.

Indonesian President Susilo Bambang Yudhoyono apologized Monday for the haze that blankets his neighbors.

"For what has happened, as President, I say sorry and seek the understanding of our relatives in Singapore and Malaysia," he said, according to the Straits Times of Singapore. "Indonesia had no intention to cause this. And we will continue to bear responsibility to overcome what has happened," he said in a televised press conference at his office on Monday evening.

In Malaysia, schools closed in the capital Kuala Lumpur and several states Monday.

"The schools are ordered to be closed as a precautionary measure since the bad air quality will affect the health of students," Second Education Minister Datuk Seri Idris Jusoh said, according to a CNN report.

In one district of southern Malaysia near Singapore, the Air Pollutant Index rating reached 746 on Sunday, the highest level recorded since the late 1990s, according to an AFP report. Though by later Monday the pollution index in one of Malaysia's worst-hit areas fell to 148, CNN reported.

On Monday in Singapore, the air quality was reported as "good," an improvement from Saturday's "harmful" level.

But Singapore officials urged for people to not be complacent.

"We must expect the haze to come back," Singapore's Prime Minister Lee Hsien Loong said, according to AFP, which also reported Singapore's Environment Minister Vivian Balakrishnan saying that "the improvement in the air quality is due to a change in the direction of the low-level winds over Singapore".

"However, we must remain prepared for further fluctuations depending on weather conditions," Balakrishnan added.

In Indonesia, about 850 hectares of forest are burning, according to The Straits Times. Reuters reported the tactic of burning forests and farmland is considered a "cheap and quick" way to make room for commercial palm oil plantations.

Last week Balakrishnan said "No country or corporation has the right to pollute the air at the expense of Singaporeans' health and well-being."

According to a New York Times article, Indonesian officials counter that Singaporean and Malaysian corporations are to blame because palm oil companies they control can be linked to the areas where the burning is taking place.

Most of the fires are on land owned or operated by timber companies and palm oil plantation owners, CNN reported, citing the World Resources Institute, which named 17 timber companies and 15 palm oil companies, including two headquartered in Singapore.

Indonesian President Yudhoyono said there would be no discrimination when it came to laying down the law on those responsible for the fires.

"Whether it is an Indonesian company or foreign company, the law will be applied firmly and fairly," he said.

Attempts to quell the fires by creating rain through a technique called cloud seeding have not had favorable results.

"So far we had two sessions of cloud-seeding, one on Saturday evening and one yesterday evening. Some rain has fallen over Dumai city (in Riau province)," Indonesian disaster agency official Agus Wibowo told AFP in Jakarta.

"The cloud-seeding technology is meant to speed up rainfall, but with few clouds, there's little we can do. The rain was more like a drizzle."