Kuala Lumpur – Malaysia has urged Indonesia to tackle the forest fires it blames for the choking haze that has engulfed the region.

Deputy Prime Minister Najib Razak said cooperation was ongoing with Indonesia over forest fires on Indonesia's Sumatra island and Kalimantan on Borneo island, but placed responsibility squarely on Jakarta's shoulders.

"As far as we are concerned, there is not much that we can do about the Indonesian fires," Najib was quoted as saying in the New Straits Times. "Our ability to resolve the problem will largely depend on the determination of the Indonesian government to address the matter. This will be our major challenge."

Air quality in parts of Malaysia's eastern Sarawak state on Borneo last week deteriorated to unhealthy levels, prompting authorities to distribute face masks amid a sharp rise in conjunctivitis and respiratory infections.

The state got a bit of a reprieve over the weekend after rain cleared the air, returning air quality to moderate levels. Western parts of peninsular Malaysia have also seen intermittent haze in recent weeks.

Burning in Indonesia – and in some parts of Malaysia – to clear land for crops causes an annual haze that afflicts Malaysia, Singapore and Thailand as well as Indonesia itself.

In July, Malaysia and Indonesia said they would join forces to stamp out open burning in oil palm plantations.

Indonesia has outlawed land clearing by fire and has vowed to punish offenders, but weak enforcement means the ban is largely ignored.