The illegal burning of forest land in Indonesia allegedly resulted in smoke-filled skies for Singapore and Malaysia residents Thursday, the cities’ air quality being deemed as “hazardous" and "very unhealthy."

The smoky haze has caused major disruptions throughout the cities since Monday, including delays at Changi Airport due to poor visibility and suspension of fast-food delivery. One unidentified airport in Indonesia reportedly closed due to the haze. According to Reuters, the smoke was caused by forest fires on Sumatra Island in Indonesia that were allegedly set to clear land for palm oil plantations west of Singapore and Malaysia.

Singapore Environmental and Water Resources Minister Vivian Balakrishnan announced on his Facebook page that officials scheduled a meeting in Jakarta in response to the unsafe air conditions after the pollution standards index reached a record score of 371 Thursday afternoon. “No country or corporation has the right to pollute the air at the expense of Singaporeans’ health and well-being,” said Balakrishnan. “We will insist on definitive action."

Officials in Indonesia blamed companies in Singapore for contributing to the haze, claiming that “zero burning” policies were used to clear the land. “Singapore shouldn’t be like children, in such a tizzy,” said Coordinating Minister for People’s Welfare Agung Laksono.

Hadi Daryanto, a senior official at Indonesia's Forestry Ministry, said the forest fire allegations are currently under investigation. "What we know is that there are several foreign investors from Singapore involved," he said. "But we can't just blame them for this. We still need to investigate."