UPDATE 1-Thai PTT sets $6.6 bln 5-yr investment plan

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BANGKOK, Dec 23 (Reuters) - PTT PCL PTT.BK, Thailand's biggest listed firm, unveiled a five-year plan on Tuesday to spend $6.6 billion on its core oil and gas businesses despite a gloomy economic outlook and falling energy prices.

However, the 2009-2013 investment plan could be revised "as necessary in view of material change in the market environment", the energy group said in a statement.

Some 58 percent of the 229 billion baht budget is earmarked for the natural gas business, which generates more than a third of PTT's annual core earnings.

PTT runs Thailand's gas pipeline monopoly and controls more than 30 petroleum gas exploration, petrochemical and refinery businesses.

Under the plan, more than 70 billion baht will be spent in 2009, rising to 82.5 billion baht in 2010.

Some funds would be invested in the pipeline system, which mainly delivers gas from the Gulf of Thailand to PTT plants and other power producers on land.

It also set aside money for the construction of a sixth gas separation plant and an ethane plant. PTT also planned to add more stations serving natural gas vehicles (NGVs).

PTT, which is majority-owned by the government, said it would monitor the economic situation in Thailand and globally and make adjustments to its investment plan as needed.

Last week, the company said it was reviewing a plan to invest in three natural gas pipelines worth a combined 50 billion baht due to the poor economic outlook.

At 0405 GMT, PTT shares were down 0.6 percent at 167 baht, in line with the overall Thai stock market .SETI. ($1=34.53 Baht) (Reporting by Khettiya Jittapong; Editing by Darren Schuettler & Ian Geoghegan)