Labour has called for broadcasters to be forced to give more airtime to female voices on each side of the EU referendum, warning women are being "pushed out" of the debate.
Harriet Harman said the argument over Britain's future membership was "too important to be left to men" and has written to Ofcom calling for action from the regulator to ensure a better balance.
The former deputy leader said male politicians had so far outnumbered female counterparts by nearly five to one on BBC Radio 4's flagship Today programme, by six to one on BBC Breakfast and three to one on ITV's Good Morning Britain.
She will be one of several prominent Labour women holding a press conference to highlight the issue.
In her letter to Ofcom chief executive Sharon White, Ms Harman cited research by Loughborough University which found only 16% of TV appearances on EU issues had been by women.
"No woman makes the top 10 of voices heard on EU issues. Indeed, the top three voices are three white, male, Tories," she complained - Boris Johnson, David Cameron and George Osborne.
"It fails to reflect the breadth of voices involved with the campaign and as a consequence, a narrow range issues ends up being discussed, leaving many women feeling shut out of the national debate.
"The referendum campaign is too important to be left to men.
"It is absolutely vital that, before making their decision on the 23rd of June, voters have been able to hear a broad spectrum of views covering all the issues that matter to the British people."
The regulator's broadcast code said that "an appropriately wide range of significant views must be included and given due weight" in discussions of major political controversy, she pointed out
"Furthermore, last year you were quoted as saying diversity was a 'big priority' for Ofcom and that 'collective endeavour' from the media on this was important, too.
"That is why I am urging Ofcom to do what it can amongst broadcasters to help ensure women are properly represented on broadcast media and that serious issues affecting female voters are given adequate media coverage.
The Loughborough study examined 10 days of reporting in May and found 91% of national newspaper coverage involved men and 84% of TV evening news reports.