More than a million people work beyond state pension age
Politicians are being urged to scrap the default retirement age amid concerns that employers have used it to save costs during the recession.
In their pre-election manifesto, Age Concern and Help The Aged said firms were forcing people to stop work at 65 as a "cheap alternative" to redundancy.
Doing so was discriminatory and "tarnished" the lives of people affected, the organisations said.
Ministers said their "long-term aim" was to scrap fixed retirement ages.
The majority of people retire before 65, but 1.3 million people work beyond state pension age and many more say they would if their employer permitted it.
Critics say, under the current rules, employers can compel people to retire whatever their circumstances.
Age Concern and Help The Aged said there was growing evidence it was leading to "forced retirement" in the workplace.
One in four people questioned by the organisations said they knew someone who had been compelled to retire at 65, it said.
"The default retirement age has stamped an expiry date on hundreds of thousands of older workers," Age Concern director Michelle Mitchell said. "It is the most disturbing example of age discrimination which still tarnishes later life for so many people."
Pensions Minister Angela Eagle said the government was reviewing the current situation and, in the meantime, was doing all it could to encourage firms to recruit and retrain older workers.
"We are considering the evidence and, if it shows it is no longer needed, we will remove it," she said.
In its document, Age Concern and Help The Aged also called for an increase in state pensions, reform of the care system and action to tackle "malnutrition" in hospitals.