The Labour former deputy leader will give a speech on Tuesday objecting to the lack of female voices on television and radio, saying key arguments are being blocked.
She will cite Labour analysis which found that men make up 83% of all politicians who have appeared on the Today programme since the beginning of the year.
A Loughborough University report published on Monday said only one in 10 contributors to the EU debate in the national press were women. On television, fewer than one in six people on screen were women. Boris Johnson, David Cameron and George Osborne were the top three politicians most frequently featured across both media.
Speaking in Westminster, Harman will say: “Half the population of this country are women and our membership of the EU is important to women’s lives. Yet men are, as usual, pushing women out.
“Women are being excluded and the debate narrowed. The broadcasters have a legal duty to keep a balance between those who want remain and those who want to leave. They should have a balance between men and women. This referendum is too important to be left to men.”
She has written to Ofcom calling on the watchdog to ensure that women are equally represented in the broadcast media and that serious issues affecting women and the EU are given adequate media coverage.
The Loughborough report found that male sources dominated press and TV reporting over 10 weekdays between 6 May and 18 May.
Dominic Wring, professor of political communication at Loughborough University and one of the five authors of the report, said: “Conservative politicians and internal party rivalries have dominated the referendum campaign.
“Longstanding campaigners such as Nigel Farage and Alan Johnson have been comparatively marginalised. Unlike Cameron and his putative successors, Jeremy Corbyn’s profile has been similarly modest. But these male politicians have at least received some attention whereas women representatives have been seldom seen, heard or reported in this stage of the campaign.
“Nicola Sturgeon’s absence from the news reporting considered here is quite striking [and] reflects the marginalisation by the media of the constitutional implications of a vote for Brexit.”
The Loughborough study analysed the main evening bulletins on BBC1, ITV, Channel 4 and Channel 5 and a 30-minute evening slot on Sky News, as well as a representative sample of pages from all the national daily newspapers.
The report said TV news was more favourable to the in campaign than the national press, but said it was too early to say whether either side was “definitively winning the media war”.
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