The Australian offshoot of troubled Japanese car giant Mitsubishi Motors is facing the threat of closure again just two years after being rescued from collapse with $A85 million dollars ($US63 million) of government funding.

According to Agence France-Presse, Mitsubishi's 3,300 Australian workers received the news on Wednesday that the Japanese paper Asahi Shimbun had reported the parent company was considering closing and selling its South Australia plant as part of a global restructuring.

Mitsubishi Motors Australia (MMA) spokesman Charles Iles told AFP he could not confirm the truth or otherwise of the report, but agreed the workers had been informed about the speculation and were worried about it.

"They have been told about it and they are naturally concerned," Iles told AFP.

"I've been speaking to Japan about the report and they are saying there has been speculation about a number of issues 'and we're not commenting on speculation'," he reportedly said.

AFP said MMA's unions and the South Australian state government are understood to have been informed by management about the report which Iles described as speculation on what might be included in a business plan to be issued by the parent group next month.

He reportedly said the Australian subsidiary had spent more than $A200 million ($US150 million) recently upgrading the plant for the latest version of the company's long running six-cylinder Magna and was still going ahead with that.

Asked how it could go ahead with this if the plant closes, Iles told AFP: "You'll need to speak to Tokyo about that."

AFP said that MMA manufactures in Australia just one car, the six-cylinder 3.5-litre Magna, which has been judged by local car magazines among the best of four big six-cylinder locally built cars with which it competes; the rivals are Holden's Commodore, Ford's Falcon and Toyota's Camry.

But, AFP added, despite its performance and quality, the Magna has rarely been a great commercial success, at least partly because of fears surrounding the future of the plant prompted by unwise speculation about possible closure, usually by top Mitsubishi executives in Japan.

However, the promise of $A85 million in federal and state government funding in 2002 ended talk of closure of the plant which employs some 3,300 workers directly, but up to 19,000 others in component and downstream industry, the report added, noting that MMA has since worked to regain commercial viability, returning to profitability in subsequent years after losing $A186 million in 2000.

The plant, which is one of South Australia's biggest employers, has output capacity of 70,000 units a year to produce passenger cars for the domestic and export markets. It has produced cars since the early 1980s when Mitsubishi took over the plant from Chrysler and currently exports to the United States, Canada and Thailand, AFP said.