US car giant General Motors Corp. said Tuesday it is cutting production in Russia as demand declines in a market only recently described as potentially the largest in Europe. GM will slash the working week to three days after restarting the assembly line on Feb. 9 following repeated shutdowns, company spokesman Sergei Lepnukhov said. “This will last for the next few months,” he said. GM opened its new $300 million plant outside St. Petersburg in November with plans to produce 70,000 cars a year. But with the Russian market already contracting, the plant closed down for an extended holiday from Dec. 20 to Jan. 19. xProduction resumed for only one week before being shut down again.