The Welsh Government and local politicians have said the Kasai plant in Merthyr Tydfil is set to close with around 180 jobs expected to be axed.
The company, which produces internal parts for Honda, Jaguar Land Rover, and Nissan, is said to be closing its factory at Triangle Business Park in June, 2021.
This follows Honda's decision to pull out of Swindon next year, with around a fifth of sales at Kasai going to the Japanese car manufacturer.
Labour MP for Merthyr Tydfil and Rhymney, Gerald Jones, published the reports on his Facebook page.
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In a joint statement, Mr Jones and Assembly member Dawn Bowden said: "We are very disappointed to hear this announcement from Kasai, although the news does not come as a total surprise given the position at Honda in Swindon.
"This is the latest in a number of job losses in our constituency, which shows the vital importance of stepping up support and intervention for those businesses which can help to sustain local jobs."
The Welsh Government told the BBC it would offer support through its ReAct programme, adding: "[we will] continue to do all we can to explore options for the site".
This follows the news Ford's Bridgend plant is to close in September of this year. The plant employs 1,700 people directly and more in the supply chain.
Kasai has been approached for a comment.
