The British Transport Police and Network Rail, the railway operator, said that mental health services were not taking enough action to treat the increasing number of people known to be a suicide risk.

Nearly 300 deaths were recorded on the mainline network and London Underground in 2006-07, about a fifth more than in previous years. The vast majority were thought to be suicides, transport officers said. A separate log of incidents by Network Rail recorded 219 suicides in 2006 – the highest number for more than a decade. These caused nearly 5,000 hours of delays. Officers said that some people were being turned away by mental health services, despite evidence of previous attempts to kill themselves on the railways.

Opposition parties have suggested that cuts to mental health services could be responsible for a spate of recent cases where local authorities refused to admit patients to hospital.

Norman Lamb, the Liberal Democrat health spokesman, said: “Access to mental health services is not as good as it should be, in part because of cutbacks in the NHS.”