Siam Cement PCL, Thailand's largest industrial conglomerate, beat market expectations with a 63 per cent rise in quarterly net profit, boosted by better petrochemical margins and a pick-up in domestic cement demand.

Domestic cement demand should grow by five to six per cent in the second half after a two per cent rise in the second quarter, as demand from government projects and commercial sectors recover, chief executive, Kan Trakulhoon,  said.

"This is the first time since the second quarter last year that domestic cement had positive growth. Going forward, we are confident in second half," he said.

Net profit was THB13.88bn (US$397.5m) for the April-June period, exceeding a median forecast of THB11bn from six analysts surveyed by Reuters. This compares with a profit of THB8.53bn in the same quarter a year earlier.

The weakness of the baht against the dollar should help boost Thai exports and the overall economy, while the company is on track to invest in cement expansion in Cambodia, Indonesia and Myanmar, Mr Trakulhoon, said, adding Myanmar and Cambodia had strong cement demand of more than 10 per cent in the second quarter.

Sales fell nine per cent on year due to lower chemical prices, but profit from petrochemicals jumped four times because of rising margins and tight supplies, he added.