MANILA (AFP) - The Philippine island of Cebu suffered its seventh straight day of haze on Saturday (Oct 3), the weather bureau said, as Southeast Asian countries battle pollution suspected to emanate from illegal fires on Indonesian plantations.

Monsoon winds blowing northeast from the Indonesian blazes towards the direction of the central Philippines could have carried the haze, state weather forecaster Romeo Aguirre told AFP.

"We suspect that this haze is from Sumatra. It is unusually thick," Aguirre said.

Haze from local pollution is common in Cebu, home to four million people, but usually disappears within a day. The current cloud of pollution blanketing the city in a blueish-grey veil is into its seventh day, though it has thinned considerably.

The haze was thickest on Monday, halving the normal range of visibility to 5km around the same time typhoon Dujuan was forecast to pass over Cebu, Aguirre said.

The environment department is expected to conduct further tests to confirm the haze's provenance, he added.

Malaysia, Singapore and large portions of Indonesia have for weeks choked on pungent smoke from forest fires on Sumatra Island.

The fires are on track to be the worst on record, surpassing the US$9billion (S$13 billion) damage from a similar incident in 1997, Nasa warned on Friday.