DETROIT, Mich. (AP) _ General Motors Corp. will buy more than $1 billion in recycled aluminum over the next 13 years to use in making engines and components.

The automaker has agreed to buy all of the recycled aluminum that Imco Recycling Inc. will produce at a new plant it plans to build in Zilwaukee. The plant will be situated near a GM Saginaw Metal Casting Operations, a powertrain facility.

``We think this is a tremendous win for our foundry in Saginaw because it provides a solid future for our employees and provides numerous environmental benefits,'' John Stiles, executive director of GM purchasing of metals, said Wednesday.

The agreement with Imco, which is based in Irving, Texas, calls for almost 2 billion pounds of recycled aluminum over the next 13 years.

Recycled aluminum has become the largest single component of the national auto supply, said Imco chairman Don Ingram.

Ingram said about 65 percent of the aluminum used in automobiles is recycled metal. He said the percentage could rise as more usable scrap become available.

The deal with Imco is the third major aluminum agreement GM has made in the last four months. In November, GM announced a 10-year agreement with Alcan Aluminium Ltd. to buy aluminum.

Shares of Imco rose almost 25 percent, or $2.93 3/4 to $14.75 on the New York Stock Exchange.