BANGKOK Nov 14 (Reuters) - Thailand's Electricity Generating Pcl (EGCO) said on Monday it had submitted a bid for a stake in GS Power, a subsidiary of South Korea's GS Caltex, as part of an expansion drive. 

"We have already submitted the bid," President Sahust Pratuknukul told Reuters. He gave no further details. 

GS Caltex, South Korea's second-largest crude oil refiner, wants indicative bids for a 50 percent stake in fully owned subsidiary GS Power by Nov. 14, a company spokesman said, in a deal reportedly worth up to 500 billion won ($448.9 million). 

GS Caltex had no comment on whether EGCO had submitted a bid. 

EGCO was one of two potential buyers reported by local media to have shown interest in the stake. The other was Japan's Chubu Electric Power. 

EGCO, Thailand's second-largest private power producer, has changed its investment policy and is looking to buy assets outside Southeast Asia after a change in its shareholding structure, the company has said. 

It has interests in 14 power plants in Thailand, Laos and the Philippines with a combined capacity of about 4,417 MW and accounts for about 12 percent of Thailand's generating capacity ($1 = 1113.900 Korean Won) (Reporting by Khettiya Jittapong and Wilawan Pongpitak and Ju-Min Park in Seoul; Editing by Alan Raybould)