Work and Pensions Secretary Iain Duncan Smith has denied he is planning to make people "work until they drop" by increasing the retirement age.

He said moves to keep people working for longer were not about saving money but about making the best use of talent in the workforce.

Higher levels of life expectancy mean that people are spending as long as 28 years in retirement, the former Tory leader said.

"The simple point is not about saying to people: work until you drop," Mr Duncan Smith told BBC Breakfast.

"Working an extra year or two isn't about working until you drop. This has not been announced as a money-saving measure. It was already about the question: how do we best use the talents of people for longer? One of the things we want to do is to get rid of the default retirement age.

"At the moment, many companies can say to somebody who reaches 65 'That's it, you've got to go'. We have been contacted by lots of people out there who say 'We want to go on working beyond that, maybe by a year, maybe two years, because it helps our income'.

"When the retirement age was set in 1940, most people, on average, could expect to live for another seven years and then die. The reality now is that anything up to 28 years is the time after retirement that people expect to live. The key thing is it does give talent back into the economy where we are going to be missing, losing that over the next few years."

The Government put forward plans to scrap the default retirement age, which allows employers to get rid of staff when they reach the age of 65.

The state pension age for men is set to rise from 65 to 66 from 2016, nearly a decade earlier than the last government was planning, while ministers also raised the possibility of extending the pension age to 70 and even older in the following decades to "reinvigorate retirement". The Government called for evidence about the right point at which the state pension age should rise to 66 for both men and women.

Unions have reacted with fury, accusing the Government of showing its "class bias" just weeks after gaining power.