They said buying sentiment was also buoyed after the finance minister said Thai Petrochemical Industry, the country's biggest corporate defaulter, is likely to complete its restructuring by early next year. The Stock Exchange of Thailand (SET) composite index rose 6.61 points to 699.88 and the blue chip SET 50 index increased 5.24 points to 490.76.
Turnover stood at 2.6 billion shares worth 18.6 billion baht (464 million dollars) traded. Gainers outnumbered losers 189 to 96, with 110 stocks unchanged.
"Overall gains in other Asian markets supported buying sentiment. Foreign investors continued buying energy and banking shares," said Sukbir Khanijoh, an analyst at Trinity Securities.
He said sentiment was also positive after Thai Finance Minister Thanong Bidaya said Wednesday that Thai Petrochemical (TPI) would finish its debt restructuring by early 2006.
The company collapsed during the 1997 Asian financial crisis with debt mounting to 2.7 billion dollars, becoming Thailand's biggest corporate defaulter. The Thai baht closed on Wednesday at 40.84-87 to one dollar, little changed from Tuesday's 40.80-83 to one dollar.
Against the euro, the Thai unit closed at 49.07-11, against Tuesday's 49.00-10.
Among major shares, Thailand's top energy firm PTT rose 4.00 baht to 226.00 while its subsidiary PTT Exploration and Production also gained 4.00 to 432.00.
National Petrochemical gained 2.00 to 130.00.
Thailand's biggest commercial lender, Bangkok Bank, rose 2.50 to 101.00 and the country's fourth biggest bank Siam Commercial Bank added 0.75 to 49.00.
Thai Airways International rose 0.25 to 38.25.