JAKARTA, Oct 16 — Four people died on Indonesia’s Java island fighting the blazes that have been sending toxic smoke across southeast Asia, closing schools and fuelling a surge of respiratory complaints in the region, authorities said today.

The impact of the months-long fires has prompted Singapore’s leader to vow legal action against any companies responsible for the blazes that have made regional air quality among the world’s worst.

Singapore again topped IQAir’s live ranking of the world’s most polluted major cities today, with Kuala Lumpur second and Jakarta sixth.

“Where warranted, we will take action under Singapore’s Transboundary Haze Pollution Act, and also explore joint action with other countries,” said Singapore Prime Minister Lawrence Wong, without giving further details.