PTT Pcl, Thailand’s largest energy company, said it agreed to buy the coal assets of Australia’s Straits Resources for A$544.1 million ($703.5 million).

PTT will pay A$1.72 a share for Straits’ 40% stake in PTT Asia Pacific Mining Pty Ltd. following a planned demerger of Straits’ coal and metal assets, it said in a statement today. The deal will give PTT full ownership of PTT Asia Pacific.

PTT Asia Pacific owns 45.6% of Singapore-listed Straits Asia Resources, operator of the Sebuku and Jembayan coal mines in Indonesia. PTT Asia also forms part of a joint venture to explore coal resources in Brunei and is a shareholder in coal deposits in Madagascar.

Straits Resources said Nov. 2 it expects the demerger to complete during the first quarter next year.

Straits Resources was down 1.8% at A$1.94 when trading in its shares was halted in Sydney today. PTT was up 0.6% in Bangkok as of 10.35 a.m.

Straits Asia produced 10.5 million tonnes of energy coal last year. Interest in coal assets has been driven by India’s growing demand as its electricity use increases, Straits Resources Chief Executive Officer Milan Jerkovic said Oct. 12. Thermal coal prices, set annually, rose 40 percent this year to $98 a ton, according to an Oct. 6 Morgan Stanley report.