Indonesia is considering declaring a national emergency over fires that have been smoldering across the archipelago for weeks, sending haze drifting across much of Southeast Asia, the vice president said on Tuesday.

The government would intensify efforts to contain the fires that have caused pollution levels across the region to spike to unhealthy levels, and forced school closures and flight cancellations, Vice President Jusuf Kalla said.

"The problem is too big," Kalla said in an interview at his office in Jakarta.

"We are now considering to," he said, referring to a declaration of an emergency, adding that thousands of troops would be deployed to help combat the fires.

President Joko Widodo is expected to make a decision on the emergency after returning from the United States, Kalla said.

Kalla's comments come just a day after Widodo announced he would cut short his first official trip to the United States to fly directly to the haze-affected areas.

"He will be more focused on domestic problems," Kalla said of the president's decision to cancel his visit to Silicon Valley, where he was expected to discuss investment deals with Apple and Google executives.

The fires, often deliberately set by plantation companies and smallholders, have been burning for weeks in the forests and carbon-rich peat lands of Sumatra and Kalimantan islands.

Recently, they have spread to places like Papua as the El Nino weather phenomenon exacerbates the dry season and hampers firefighting efforts.

An aide to the vice president, Wijayanto Samirin, said elevating the crisis to national emergency status would allow the government to speed up procurement processes for much-needed foreign firefighting equipment.

But he added there were concerns that businesses could use the government action to declare force majeure on deals in sectors ranging from palm oil to banking.

Kalla said about 40 million Indonesians in five provinces had been affected by the haze. The national disaster agency said late on Monday that haze was starting to spread south toward Java island, where over half the country’s population lives.

Indonesia has also deployed warships to evacuate infants and other vulnerable residents of haze-hit areas, a minister said last week.

The evacuations will be a last resort, said coordinating security minister Luhut Pandjaitan, if authorities are unable to provide care for those suffering from respiratory diseases.

The last time the country declared a national emergency was when the Indian Ocean tsunami killed more than 100,000 people in 2004.