The BBC and other major broadcasters are accused today of making women aged over 50 "invisible" and should be "named and shamed" for not putting older female presenters on screen.
Harriet Harman, Labour's deputy leader and shadow Culture Secretary, has written to seven broadcast chiefs demanding full details of how many women of 50 and over are employed as newsreaders, presenters and reporters.
She said younger women in broadcasting were "blazing trails" but "meet an untimely end" as soon as they reach 50 thanks to a combination of ageism and sexism. The findings of the audit will be published later this year by Labour's Commission on Older Women.
The move follows high-profile complaints of discrimination against older women on TV, including the former Countryfile presenter Miriam O'Reilly, who won an employment tribunal against the BBC after she was dropped from the programme.
Ms Harman said: "There is a real old-fashioned culture in broadcasting which is about having a partnership of an older man and a younger woman. Men remain in broadcasting as they grow older, but for women the clock ticks and they disappear off the screens as they get older."
She said all broadcasters were "as bad as each other" but listed 24-hour news programming, the BBC One's Question Time, presented by 74-year-old David Dimbleby, This Week, presented by Andrew Neil, 63, and ITV's The Agenda, presented by 46-year-old Tom Bradby.
The MP added: "Women have made great strides in terms of interviewing, reporting, presenting, but then they are swept under the carpet. This is the next frontier of discrimination.
"This is a total squandering of ability and expertise. It is rude to the viewers who are older women because it says to them you are invisible. This is about the presentation of the world seen through the eyes of younger men, older men and younger women. You never see it through the eyes of older women."
Ms Harman has written to seven broadcast chiefs, including Tony Hall, the new BBC director-general, Adam Crozier, ITV's chief executive, David Abraham at Channel 4 and John Ryley, the head of Sky News.
Labour's Commission on Older Women's includes Ms O'Reilly and Arlene Phillips, the 69-year-old former Strictly Come Dancing judge.