Prime Minister Lee Hsien Loong said on his Facebook page that Singapore's foreign and environment ministers had spoken to their Indonesian counterparts to "register our serious concerns and offer our help to fight the fires".
"We are monitoring the situation closely and will stay in close touch with the Indonesian authorities," he said in a posting accompanied by a photograph of the Istana government complex grounds shrouded in haze.
Singapore's Pollutant Standards Index again shot above the "unhealthy" threshold of 100 late Tuesday after easing earlier in the day.
Singapore Foreign Minister K. Shanmugam said he and his Indonesian counterpart Marty Natalegawa "agreed that officials on both sides should meet soon to discuss how best to combat the haze issue".
Also Read
Vivian Balakrishnan, Singapore's minister for environment and water resources, said of the smog: "This is the worst in seven years and has practically become a permanent fixture every year."
He suggested that Indonesia name the companies responsible for the fires.
"We need to exert commercial pressure against companies causing the haze," Balakrishnan said.
"We hope the governments of Malaysia and Singapore will tell their investors to adopt proper measures so we can solve this problem together."
Regional environmentalists said the problem must be tackled by both Singapore and Indonesia.
Indonesia is Southeast Asia's largest nation while tiny Singapore, just minutes away by fast boat from Indonesian territorial waters, is the region's financial hub.
"Singapore is saying that Indonesia needs to enforce the law," Bustar Maitar, head of Indonesia Forest Campaign at campaign group Greenpeace International, told AFP.