General Motors’ chairman and chief executive Rick Wagoner is taking personal charge of the giant carmaker’s troubled North American operations under a management shake-up announced yesterday.

Wagoner’s move is acknowledgement that the Detroit carmaker’s fortunes will stand or fall by the performance of the North American unit, which is struggling to maintain profitability in the face of a slide in market share and high costs.

The move frees vice chairman Bob Lutz to concentrate on global product development and group vice president Gary Cowger to focus on global manufacturing and labour.

Those two men had been responsible for GM North America, together with their individual responsibilities.

GM warned last month that the North American automotive business was in far worse shape than the company thought at the start of the year.

The stock plunged and their had been speculation of a boardroom cull.

"As we look at our global business, it's clear that the two areas most critical to our future success are achieving excellence in every product we develop, and doing it with the most competitive manufacturing system," Wagoner says in a news release.

"And Bob and Gary are our two executives most experienced and skilled in these key areas."