Mark LaNeve, GM vice president, said many of the dealers notified this week were selling 35 or fewer vehicles per year.

Barack Obama, the US president, has given GM until June 1 to restructure its debt, agree concessions with its workers union and prove it can survive as a viable business.

GM announced in April that it was to slash a further 21,000 jobs and close plants and dealerships, while Rick Wagoner, the company's former chief executive officer, was ousted by the Obama administration in March.

Chrysler, another struggling US auto-giant that has already gone into the bankrupty process, said on Thursday it plans to close 789 of its showrooms.