Bangkok  - The Thai stock market lost 2.7 per cent in value Wednesday on investor concerns over a government proposal to lower petrol prices by forcing refineries to take smaller profit margins.

The Stock Exchange of Thailand (SET) index ended at 832.99, down 22.61 points, or 2.7 per cent.

"The fall reflects concerns by investors that the government plans to force refineries to cut their profits margins in order to stabilize petrol prices for the public," said Mongkol Phuangpehtha, an analysts at Adkinson Securities.

Thailand's Energy Ministry has threatened to declare a "national emergency" in oder to force local refineries to reduce their profit margins in order to stem the rising price of petrol and diesel at the pumps.

There are several refineries listed on the SET including Thai Oil, PTT Aromatics, IRPC, Bangchak Petroleum and ESSO. All witnessed dramatic falls on Wednesday, dragging down the entire index, brokers said. (dpa)