The American team, who had an entry for the 2010 season but failed to be ready in time, has completely closed down its operations at its Charlotte base.

In the past week, permanent layoff notices were sent in writing to all of the USF1 staff, who until now had been on unpaid leave.

In the letters, team principal Ken Anderson noted that the employees might be rehired in the future "if business conditions improve", but explained that "serious economic and funding challenges" have ended the project.

It emerges that up to ten of the employees have filed grievances with North Carolina's Department of Labor over unpaid wages.

Anderson could not be reached for comment, and sporting director Peter Windsor was not mentioned in the layoff notice.