Four authors have resigned from JK Rowling’s literary agency after they reportedly declined to issue a public statement in support of transgender rights.

Drew Davies, Fox Fisher and Ugla Stefanía Kristjönudóttir Jónsdóttir quit their roles at Blair Partnership, which is based in London, because they believed the company couldn’t “support our rights at all avenues”.

Another author has quit the agency but wishes to remain anonymous.

Davies, Fisher and Jónsdóttir said they asked Blair Partnership to “reaffirm their commitment to transgender rights and equality” following the Harry Potter author’s transphobic comments on Twitter earlier this month.

“After our talks with them, we felt that they were unable to commit to any action that we thought was appropriate and meaningful,” they wrote in a joint statement. “Freedom of speech can only be upheld if the structural inequalities that hinder equal opportunities for underrepresented groups are challenged and changed.

“Affirmations to support LGBTQIA people as a whole need to be followed up by meaningful and impactful action, both internally and publicly. As LGBTQIA writers ourselves we feel strongly about having an agency that supports our rights at all avenues, and does not endorse views that go against our values and principles.”

They extended their solidarity to the trans community and others who might feel “vulnerable, alienated and unsupported” and stated facts such as: “Trans women are women, trans men are men and non-binary identities are valid.”

Davies, Fisher and Jónsdóttir also made a collective donation to Shakti Women’s Aid, which is part of the Scottish Women’s Aid movement and supports BAME women who have experienced domestic abuse.

“We would like to invite others to donate to them as well, or any other charity working in the Women’s Aid Movement across the UK or charities working directly with transgender people,” they concluded.

On 6 June, Rowling caused controversy with a series of harmful tweets – and later a 3,600 word essay on her website – about trans people, arguing that only women menstruate and weighing in on the tired ‘trans bathroom’ debate.

“When you throw open the doors of bathrooms and changing rooms to any man who believes or feels he’s a woman – and, as I’ve said, gender confirmation certificates may now be granted without any need for surgery or hormones – then you open the door to any and all men who wish to come inside. That is the simple truth,” she wrote.

Rowling’s anti-trans rhetoric was met with backlash from the LGBTQ+ community and various celebrities such as Mara Wilson, Zara Larsson, Jonathan Van Ness, Jameela Jamil, Juno Birch, Sarah Paulson and Bob the Drag Queen.

Several stars from the Harry Potter franchise also publicly voiced support for trans rights, such as Daniel Radcliffe, Emma Watson, Rupert Grint, Eddie Redmayne, Bonnie Wright, Katie Leung and Evanna Lynch.

Related: Mermaids writes open letter to JK Rowling following her anti-trans tweets.