BANGKOK (Reuters) - Major Japanese auto manufacturers will invest 150 billion baht ($4.34 billion) in Thailand over the next five years, a Thai government spokesperson said on Monday, supporting the Southeast Asian country's transition to making electric vehicles.

Toyota Motor and Honda Motor will invest about 50 billion baht each, while Isuzu Motors will invest 30 billion baht and Mitsubishi Motors 20 billion baht, spokesperson Chai Wacharoke said, adding this would include the production of electric pickup trucks.

Thailand's Prime Minister Srettha Thavisin concluded a trip to Japan last week.

Southeast Asia's second-largest economy is the largest car producer and exporter in the region. Japanese manufacturers have dominated the Thai auto sector for decades, but Chinese EV makers have recently been making large investments.

The investment by the Japanese automakers will support the government's policy of transitioning from combustion engine vehicles to EVs, Chai said.

Toyota, Honda, Isuzu and Mitsubishi did not respond immediately to requests for comment.

Thailand is aiming to convert about a third of its annual production of 2.5 million vehicles into EVs by 2030 and is preparing incentives to encourage more investment and conversion into EV manufacturing.

Tax cuts and subsidies rolled out by Thailand have already drawn a raft of Chinese carmakers, including BYD and Great Wall Motor, which have committed to investing $1.44 billion in new production facilities in the country.

Srettha this month showed executives from U.S. EV maker Tesla industrial estates in Thailand for potential investment.

($1 = 34.5800 baht)

(Reporting by Chayut Setboonsarng; Editing by Edmund Klamann and Jamie Freed)