Mitsubishi will spend THB4-5bn (US$130m-$163m) next year to upgrade three Thai car assembly plants to increase output of existing models and prepare for new vehicles.

Nobuyuki Murahashi, president of Mitsubishi Motors (Thailand), told the Bangkok Post THB1bn would be to increase production capacity at the third plant at Laem Chabang.

The third plant, which currently produces Mirage eco-cars for domestic and international markets, started commercial production early this year with an annual capacity of 150,000 units.

Mitsubishi will increase the capacity of the third plant to 200,000 units next year to meet the rising demand for Mirages at home and abroad.

Another THB3-4bn will be used for maintenance of the first and second plants, also in Laem Chabang, [Mitsubishi makes most of the pickup trucks it sells worldwide in Thailand] and for equipment replacement to prepare for the production of new models.

The first and second plants presently have a combined annual capacity of 310,000 vehicles.

Once the third plant expansion has been completed, the Thailand plant will become the world's largest vehicle production base for Mitsubishi Motors Corporation, Murahashi told the paper.

The plants in Japan will only produce vehicles for the domestic market and as a base to develop new technology.

Murahashi said Mirage production in Thailand is 13,000 units per month - 4,000 for the domestic market and 9,000 for export, mainly to Japan, Indonesia, the Philippines and Brunei.

Since the domestic demand for Mirages is growing rapidly, Mitsubishi will increase monthly output to 6,000 vehicles by the end of the year.