Toyota Motor Corp said on Wednesday it would not restart production at most of its idled Japanese vehicle assembly factories next week, denying a Nikkei newspaper report.

The world's biggest automaker has halted vehicle assembly at all but two of the 18 group-wide factories in Japan that build Toyota and Lexus cars since the March 11 earthquake and tsunami disrupted supply of components to automakers inside and outside Japan.

'There will be no resumption of production at most of our domestic factories next week,' a Toyota spokeswoman said. The company will announce its decisions as they are made, she said.

Japan's Nikkei business daily reported earlier that Toyota would reopen most of its domestic automobile plants as early as next week to start producing a limited number of models.

Toyota had lost potential production of about 200,000 vehicles as of April 1, it said, with Wednesday marking the 18th day of suspension at most of its Japanese factories.

Ratings agency Moody's Investors Service put its credit rating of Toyota under review for a possible downgrade on Wednesday, citing disruptions to its supply chain. It also cited Toyota's relatively high dependence on the Japanese market, which could be hit by weak consumer sentiment, in placing the Aa2 long-term senior unsecured and issuer ratings under review.

While Toyota's factories have not suffered major damage, the disaster has disrupted shipments of key components and 'normal production cannot be expected for many months', Moody's said in a statement. It said a rating cut of multiple notches was unlikely, given the company's strong balance sheet.

Toyota is currently assembling three hybrid models, including the Prius, at a reduced line speed at two domestic factories. It is also making replacement and other parts for overseas markets, though not at full capacity.

Among other major Japanese automakers, Honda Motor Co has said it aims to restart production at all domestic plants next Monday at a rate of about half its original plans.

Nissan Motor Co plans to resume normal production with parts procured from suppliers, rather than using inventory, from mid-April at limited operation levels. – Reuters