Leading female figures at the BBC have taken to social media to mark Equal Pay Day and increase pressure on bosses to address the broadcaster’s gender pay gap.

High-profile presenters and journalists took photos of themselves, sometimes with a male colleague, holding pictures of “=” signs and calling for equal pay on the day when, because of the gender pay gap, women in the UK effectively begin to work for free until the end of the year.

Figures released on Friday revealed thegap has been stuck at 14% for the last three years, and is widening for women in their 20s.

The BBC came under fire recently after it was revealed that several high-profile female employees had salaries significantly lower than their male counterparts. Only four women were among the top 20 earners.

The presenter Clare Balding tweeted a joke video of herself and fellow female employees from radio and TV – presenters Jane Garvey, Sue Perkins and Sabrina Grant, and journalists Lucy Siegle and Razia Iqbal – being “mothballed for hibernation” by the comedian Anneka Harry.

The Radio 4 Today programme presenter Sarah Montague tweeted a picture of herself presenting the show wearing a T-shirt with an equals sign and the words: “Happy #EqualPayDay! #bbcwomen”. Montague said the BBC gender pay gap was unfair and professionally damaging after it was revealed that she earned less than £150,000, while fellow presenter John Humphrys was paid between £600,000 and £649,000.

Co-presenter Mishal Husain tweeted a picture of herself holding the same symbol adding: “Closing the gender pay gap is about equality. It should matter to everyone.”

DJ Jo Whiley snapped herself with Radio1 colleague Greg James, saying: “It all adds up”.

Victoria Derbyshire, who hosts a current affairs show on BBC, tweeted the same image calling on “bosses of small firms, large corporations, charities, startups, multinationals” to “do the right thing”. 

Garvey, who presents Woman’s Hour and was among the female staff who called on the corporation to take urgent action to “rectify injustices” over pay, tweeted a tongue-in-cheek message, writing: “New scientific research I’ve just invented says only well-endowed men can fully support closing the gender pay gap.”

The presenter and last year’s Strictly Come Dancing champion, Ore Oduba, tweeted his support with a picture of Jodie Whittaker, the new Doctor in Doctor Who, saying he was “inspired by the Timelord today”.