Forest fires in Indonesia burn hundreds of thousands of hectares, sicken residents and send thick haze across the region. (AFP pic)SINGAPORE: Air pollution in part of Singapore hit the country's "very high" band on Wednesday while East Timor shut schools, as haze from forest fires raging in Indonesia causes a regional crisis.

The blazes in Indonesia have burned through hundreds of thousands of hectares of forest and plantations on Borneo and Sumatra islands, sickened local residents and sent thick haze across the region.

Air pollution in western Singapore on Wednesday hit "very high" - the country's top level - the National Environment Agency said.

It recorded levels of tiny particulates capable of penetrating the bloodstream and lungs, known as PM2.5, at 288 micrograms per cubic metre, vastly exceeding the World Health Organization's recommended average annual exposure of five micrograms.