Singapore and Malaysia have again been blanketed in smog from forest fires in Indonesia.
The latest fires on Sumatra this month triggered health alerts in Singapore and parts of Malaysia.
Singapore Foreign Minister George Yeo has urged his Indonesian counterpart Marty Natalegawa to take action, and has offered assistance to help put out the fires.
The fires have mostly been lit by farmers clearing land for cultivation.
The problem of haze from Indonesian forest fires has been acknowledged by the Association of Southeast Asian Nations (ASEAN) for more than a decade.
In 2002, the bloc adopted a treaty on Transboundary Haze Pollution, aimed at coordinating efforts to fight the fires, but Indonesia has yet to ratify it.
Observers say pressure on Indonesia for ratification is likely to be ramped up at this week’s ASEAN leaders’ summit in Vietnam.