BANGKOK, Thailand -- General Motors Corp. said Wednesday it will invest US$445 million to build a diesel engine plant in Thailand and upgrade its existing assembly operations.

The new plant, slated to begin production in 2010, will produce engines for small pickup trucks and will have a capacity of over 100,000 units annually, the US auto manufacturer said in a statement.

The plant in Rayong province, 90 miles southeast of Bangkok, will initially employ 340 workers, the statement said.

"The new 14,492 square-meter facility will be GM's first diesel engine plant in Southeast Asia," the statement said. The plant will build four-cylinder diesel engines for use by Chevrolet in Thailand and other global markets.

The engine plant will be located next to GM's vehicle assembly plant that opened in 2000 and has a staff of about 2,000.

The existing assembly facility will also be upgraded for production of the new model Chevrolet Colorado small pickup truck, which is sold in Thailand and in export markets.

Thailand's vehicle market is dominated by pickup trucks, which account for about three-quarters of the autos made here.

Other major pickup makers in Thailand include Toyota Motor Corp., Isuzu Motors Ltd. and Mitsubishi Motors Corp.