Government proposals that could see millions of people working until they are 70 have been unveiled.
People could work up until 70 under the proposals
The plans for tackling age discrimination, which stem from a European Union directive, will mark the biggest change in employment law for a generation.
Employers are set to be banned from enforcing a retirement age below 70.
The new proposals are also designed to outlaw ageist advertising and workplace practices.
Under the new rules employers would not be allowed to stipulate the required ages for a job or to tell older employees they did not qualify for training schemes.
The legislation could see many more people working on into their sixties.
Currently employers can set compulsory retirement ages for staff.
But under the new plans that would not be allowed and they would have to allow people to work until they were 70.
The government believes that unfair age discrimination costs the economy billions of pounds - as much as £16bn a year - and stops people realising their true potential.
Ms Hewitt condemned ageism as the "last bastion" of discrimination.
She told the BBC: "We have got to get away from a situation where hundreds of thousands of people are forced out of employment usually against their will, in their fifties - sometimes in their late forties ...and then find they can't even get an interview, they can't even get a job."
Ms Hewitt said more and more people wanted to combine work and family life.
"This is not about forcing people to work until they are 70, but this is about giving people much more choice," she said.
John Cridland, deputy director general of the CBI, said employers recognised that age discrimination was unacceptable, but warned it could prove tricky to outlaw.
"Much more than any previous discrimination law, age discrimination is
particularly difficult to define."
Mr Cridland warned there was a real risk of an "explosion" of employment tribunals if workers took up any new right to challenge employers if they felt they had been discriminated against because of their age.
"Employers need to be clear, whether at recruitment or retirement, they can take common-sense decisions that are inside the law."
The measures being suggested by the government would bring the UK into line
with European Union employment law.