The firm said on Monday that profits before taxes and one-off costs for the year to April came in at £166.6m, 16% down on the previous year.

Stagecoach, which runs bus and train services in the UK and US, blamed recent disruption to the UK's railway infrastructure and a "disappointing" performance by its US subsidiary, Coach USA.

Profits at Coach USA, hit by the post-11 September downturn in the US travel industry, fell by a third to £41.2m.

Mr Cochrane had been responsible for management and strategy at Coach USA.

Coach USA under review

Stagecoach chairman Brian Souter, who has taken over as acting chief executive, said the company had accepted Mr Cochrane's resignation "with regret."

"Keith Cochrane has made a significant contribution to Stagecoach during his eight years with the group, and I would like to record my personal thanks for his hard work and dedication during that time," he said.

Stagecoach said it planned to carry out a "full review" of its US businesses by December.

The company has already pushed through a $25m cost-cutting programme at Coach USA, trimming the firm's head office staff by 40%, and taking 330 buses out of service.

In the City, Stagecoach shares were marked down 9.5p, or 18%, at 42p.

The share sell-off came despite news that railway firm Virgin Rail, 49% owned by Stagecoach, is to receive £100m compensation for delays in modernising the UK's main west coast railway line.

The delays have prevented the company from running its new, ultra-rapid Pendolino trains at full speed.