(Adds confirmation of GM plans by source, adds GM no comment)
DETROIT, Feb 25 (Reuters) - General Motors Co is cutting production at two of its North American car plants as supplies of vehicles including the Chevrolet Sonic and Buick Regal rise, a person familiar with the company's plans said on Wednesday.
Automotive News initially reported GM's plans for its plants in Lake Orion, Michigan, and Oshawa, Ontario, citing sources.
GM scheduled downtime for March 9-13 at its Orion plant outside Detroit, where the Sonic and Buick Verano cars are made, to adjust for lower demand, said the person, who asked not to be identified. The plant was also idle last week and previously had scheduled a down week April 6-10, Automotive News said.
The company's "flex" line at its Oshawa, Ontario, plant will be idled April 13-17, cutting output of the Chevy Camaro sports car, Regal sedan, Cadillac XTS sedan and Chevy Impala, the source said.
A GM spokesman declined to discuss the company's production plans.
On Feb. 1, there was a 216-day supply of Sonics on dealer lots or on the way to stores, the highest inventory level since the debut in August 2011, according to Automotive News. The inventory for Regal as of Feb. 1 was 213 days. It was 131 days for Camaro, 109 days for XTS, 92 for Verano and 65 for Impala, the publication said. (Reporting by Ben Klayman; editing by Matthew Lewis)