LOS ANGELES – Toyota on Wednesday extended production cuts at its North American and Chinese plants because of a shortage of parts after Japan’s record earthquake and tsunami last month.

The company’s North American unit said that plants in the region will continue to be closed on Mondays and Fridays and run at 50 percent on Tuesdays, Wednesdays and Thursdays through June 3. The world’s largest automaker will also shut U.S. plants for one week starting May 30 and in Canada from May 23.

In China, the utilization rate at factories will generally be 50 percent of normal levels and may fall as low as 30 percent from April 21 to June 3.

“This is not going to be over soon,” said Jesse Toprak, an analyst for Truecar.com, an automotive pricing and data website based in Santa Monica, Calif. “The impact of reduced production could mean that Toyota’s sales in the U.S. are impacted as much as 10 percent this year.”

“No one knows how long production will remain at about 30 to 40 percent of the usual level,” said Koji Endo, an analyst at Advanced Research Japan in Tokyo. “Customers who are not willing to wait for Japanese vehicles may switch to buying American, Korean and European cars instead.”