U.S. antitrust authorities said on Tuesday they would not oppose a plan by billionaire investor Kirk Kerkorian (search) to increase his stake in General Motors Corp. (GM) and possibly seek a seat on the automaker's board.

Officials have completed their investigation of the proposal without taking any further action, the Federal Trade Commission said in a notice.

In a September 21 regulatory filing, Kerkorian's Tracinda Corp. (search) , which holds a 9.5-percent stake in GM, said it intended to boost its ownership to up to 9.9 percent and might ask General Motors for representation on the board.