Time Warner described Ted Turner as a visionary leader

Mr Turner said that "after much deliberation" he had decided to step down from the company's board.

The media mogul created the CNN news channel as part of his Turner Broadcasting business, which he later sold to Time Warner.

Mr Turner, who was Time Warner's vice chairman until 2003, said he would step down at the firm's next annual meeting.

'Media pioneer'

Mr Turner remained Time Warner's largest single shareholder for some time after the sale of his group for $7.5bn (�4.3bn) in 1996.

"It is after much deliberation that I have decided not to stand for re-election at the annual meeting," he said.

Time Warner chief executive Dick Parsons described Mr Turner as a "visionary leader".

"Ted Turner's legendary record as a media pioneer and executive at Turner Broadcasting and Time Warner speaks for itself," he said.

Mr Turner, the former husband of actress and peace campaigner Jane Fonda, shot to fame as boss of the Turner Broadcasting System, overseeing networks including CNN and entertainment channel TNT.

Time Warner also announced that former US trade representative Carla Hills would not be seeking re-election to the company's board of directors.

Shares in Time Warner were down almost 1% at $17.21 in midday Wall Street trade on Friday.