DETROIT — General Motors is likely to announce further production cuts and possible plant closures as early as this week as it deals with slumping sales and a collapse in its stock price, a person with knowledge of the company's plans said Friday.

The person, who did not want to be identified because the plans are not finalized, said the cuts likely will hit engine, transmission and stamping operations to correspond with a June announcement that GM would close four truck and sport utility vehicle assembly plants.

The closure dates for those plants likely will be accelerated, the person said. GM announced recently that its Moraine, Ohio, SUV factory will close Dec. 23, and it has said it will idle assembly factories in Oshawa, Ontario; Toluca, Mexico; and Janesville, Wis., by 2010.

Chairman and CEO Rick Wagoner said last month that GM would have to make adjustments, particularly in stamping factories. Further cuts could shore up GM's share price, which lost nearly half its value this past week, plunging to the lowest level in more than 58 years. Industry analysts say closing factories or pulling off shifts will help GM cut costs and preserve cash.

GM had $21 billion in cash and $5 billion available through credit lines at the end of June for total liquidity of $26 billion but has been burning up cash at a pace of more than $1 billion a month.