A 6.8-magnitude earthquake that struck northwestern Japan Monday has damaged a key engine parts supplier and halted production in 70% of the domestic auto industry, according to media reports Wednesday.


Toyota Motor Corp. ™ and other carmakers including Nissan Motor Co. (NSANY) , Mitsubishi Motors Corp.and Suzuki Motor Corp.have temporarily halted production following damage to the main Tokyo production facilities of engine parts maker Riken Corp., according to reports.


Toyota said it would halt production at all 12 of its Japanese plants Thursday and Friday, reports said.


Stockpiled parts had kept Toyota plants running in the days immediately after the quake, and Toyota will assess its ability to re-start production next week, reports said. Toyota produces 11,000 cars a day in Japan, according to a report in The Wall Street Journal's online edition.


Riken holds a 50% market share in Japan in piston rings for engines and a 70% share in transmission sealant components, Nikkei News reported.


Mitsubishi said it will suspend production for at least three days at three major assembly plants, the Journal reported, adding that Suzuki expects a production loss of 10,000 cars due to shutdowns at five plants.


Honda Motor Co. (HMC) said some of its production could be halted next week, the report said, while Fuji Heavy Industries Ltd., which makes Subarus, said production will be halted at five of its facilities.


Nissan said it is halting production at two facilities on Honshu for at least two days starting Friday, AP reported.


Riken also supplies parts to European carmakers, including Volkswagen AG ( VLKAY) and BMW AG, the Journal reported.


Volkswagen said its production has not been affected, according to the report, while BMW was unable to say whether its production will be affected.