AUGUSTA, Ga. — Georgia-Pacific Corp. said Tuesday it was considering selling some mills, box plants and timberland in the wake of its pending $4 billion acquisition of Great Northern Nekoosa Corp.

The company’s board of directors authorized management to explore the sale of as many as 20 of its mills and plants following its annual shareholders’ meeting in Augusta.

Chairman T. Marshall Hahn Jr. said timberland required to support the plants also may be sold. He said the properties “may not fit our long-term strategy.”

“We have determined certain container board and packaging assets, along with associated timberland required to support them, may not fit our long-term strategy,” said Hahn. “Our board of directors has approved a plan to explore their sale.”

Assets being considered for sale are a linerboard mill at Valdosta, Ga.; a linerboard, corrugating-medium and kraft paper mill at Toledo, Ore.; and a corrugating-medium mill at Tomahawk, Wis.

Also under consideration is the sale of box plants in the following locations: East Point, Ga.; Garland, Texas; Milan, Mich.; Modesto, Calif.; Newark, Ohio; Newberry, S.C.; Rutherfordton, N.C.; Salisbury, N.C.; Milwaukee, Wis.; Minneapolis, Minn.; Olympia, Wash.; Buffalo, N.Y.; Grafton, W.Va.; Miami, Fla.; Bristol, Pa.; Gas. City, Ind.; and Los Angeles, Calif.

The plants were targeted because of a “geographic or product redundancy” due to the planned acquisiton of Norwalk, Conn.-based Great Northern, according to Sheila Weidman, a company spokeswoman. She said Georgia-Pacific wasn’t in need of cash to complete the merger, which is expected to become final by the end of June.

Ms. Weidman declined to place a value on the assets that may be sold, although the company announced last month it would sell at least $1 billion in assets to cut costs, raise capital and reduce debts.