Legal experts yesterday warned that companies face losing millions of pounds if they do not alter their employment contracts before new age discrimination legislation comes into force.

Age discrimination will become unlawful from October 1 when the Employment Equality (Age) Regulations 2006 take effect.

But Richard Linskell, employment partner at Dawsons Solicitors, said millions could be lost in tribunal claims if employers are found to be at fault.

"This will be one of the most important pieces of legislation in the history of UK employment law," he said.

"It could cost UK businesses substantial amounts of money if they are found to be discriminating against employees on the grounds of age."

In recent weeks, there has been considerable comment over the retirement date of BP's esteemed chief executive, Lord Browne.

Although Lord Browne confirmed he would step down in 2008 at the age of 60, he said it was nothing to do with his age but rather the length of time he had worked at the company.

He told the company's AGM last week he would not be retiring but moving jobs.