Managers prejudiced against older employees are being urged to change their attitudes before new age discrimination rules kick in next year.

The call has come from Bradford South MP and Employment Minister Gerry Sutcliffe, who warned bosses they faced tribunals if they ruled out workers on the basis of age.

Mr Sutcliffe was speaking as a new survey revealed alarming levels of prejudice among Britain's managers.

A survey of 1,000 executives by Eversheds Solicitors and the Cranfield School of Management found that one in four believed workers aged 50-plus were over the hill. The survey revealed that stereotypes persisted with a third of those questioned saying older workers were unreliable and unwilling to change. Audrey Williams, of Eversheds, said it was worrying that senior managers entertained these attitudes. "In just 12 months, employers will be liable if their employees take decisions based on an individual's age," she said. "From these findings it would appear that businesses have got a mountain to climb if they are going to change negative attitudes towards age which appear to be ingrained in UK workplaces." Mr Sutcliffe warned that many managers could find themselves in "confrontational situations" with older employees if they refused to change their minds. He said: "One of the barriers to change has been the attitude of managers," said Mr Sutcliffe. "We're living longer and there are demographic changes as well as fewer people in the workplace. So there has to be a reappraisal of the jobs on offer.

"I don't accept that elderly workers have the inability to change. Some managers need to look at their attitudes. And firms should be looking at developing their middle managers and looking at the bigger picture."

He hoped there would not be an upsurge in workers taking action against companies.

Sandy Needham, chief executive of Bradford Chamber of Commerce, said: "If only one-third of bosses believe that older workers are unreliable, does that mean that two-thirds think they are more reliable? We would challenge that view anyway. Also, if 25 per cent of bosses think over 50s are over the hill, maybe 75 per cent of them don't.

"The study is right, though, to flag up the forthcoming legislation on age discrimination in the workplace, which, if not amended, could create some confusion."