A survey of 2,000 adults by insurers Friends Life showed that two out of five have suffered from stress, anxiety or depression in the past year and not told their boss.

More than one in four of those surveyed said they had taken a day off sick and claimed that it was for a physical rather than mental health problem.

The most common cause of stress was excessive workload, followed by frustration with poor management and long working hours, the study found.

More than half of those polled said their career prospects would be damaged if they were open about stress or anxiety.

Younger workers were more likely to suffer from depression, anxiety or stress, said the report.

Friends Life group chief executive Andy Briggs said: “These statistics paint a worrying picture of a culture of silence when it comes to mental health.

“Our research shows that there is still much to be done in tackling mental health issues in the workplace.”