Mr York questioned the future of the Hummer subsidiary

Jerome York said it was time for GM "to go into crisis mode" and warned that Mr Kerkorian had not ruled out pushing for the carmaker's board to be changed.

Speaking at the Detroit motor show, Mr York added that GM should consider selling its loss-making Saab unit.

Shares in GM have fallen to a 20-year low as losses have hit $4bn (�2.2bn).

Numerous woes

The carmaker, which has been knocked by falling sales and high costs, recently announced it was closing 12 North American plants and cutting 30,000 jobs.

It has also agreed a deal with unions to reduce its staff healthcare obligations by $1bn a year.

Mr Kerkorian owns 10% of GM's shares though his Tracinda investment company.

Dubbing Saab a "pretty consistent money loser", Mr York also questioned the future of GM's giant Hummer four-wheel drive vehicles, and whether directors should take a pay cut.

"When a company is in deep trouble - and make no mistake, GM is at the present time - there are only so many hours in the day for management to effectively focus on and fix things," he said.

"That focus needs to be on the important levers that can really move the needle."

Chief economists from GM, Ford and DaimlerChrysler's US Chrysler arm predict that US sales of cars and trucks will fall modestly this year.

In a joint statement, they expect overall sales of between 16.7 million and 16.8 million, down from 2005's 16.9 million figure.