General Motors was dealt another blow yesterday when a second credit agency cut its debt rating to "junk" status.

Fitch Ratings followed Standard & Poor's, which downgraded GM this month.

A second junk rating will cement GM's status, increasing its borrowing costs and making it more difficult to raise further capital. GM has about $292bn (£160bn) in debt, the largest amount ever to fall below investment grade.

Shares in the carmaker fell 85 cents to $31.74.

GM, like Ford, faces falling market share in the US under the onslaught from Asian manufacturers; a worsening product mix as consumers turn their backs on gas-guzzling sports utility vehicles; rising raw material prices and the cost of healthcare for workers. GM fell to a $1.1bn loss in the first three months of the year, its worst performance in more than a decade.