Liberal Democrat peer Lynne Featherstone has said that women are not welcome in the party if they are opposed to trans people having access to their spaces.
In a blog on the Liberal Democrat website, the former Equalities Minister said that she was fighting for trans people 'to be seen as people and welcomed into all spaces' as she blasted those who did not support opening up women-only spaces to trans women.
In the controversial piece, written in celebration of LGBT History Month, Featherstone said that those who sought to exclude trans women from women-only spaces were 'not feminists' and had no place in the party.
'I also have a message to those people who believe they can restrict trans women's rights, deny their human rights, or exclude them from women-only spaces in the name of feminism: You are not feminists. Your views are not welcome in the Liberal Democrats,' she said.
She boasted that the Lib Dems were fighting to introduce gender neutral bathrooms and gender neutral school uniforms, as well as a third 'X' gender designation on passports and official documents for those who did not wish to identify as male or female.
She also voiced support for proposed changes to the Gender Recognition Act that would allow people to self-identify their gender without the current requirements for medical evidence or proof that they have been living as their acquired gender for at least two years.
Feminists and rights groups have been among those campaigning strongly against any changes to the current law, warning of the risk to women and girls.
The Oxford Human Rights Hub has previously warned that allowing gender self-identification is open to abuse by sexual predators and could be problematic not only for survivors of sexual violence but also for people of faith, for whom sex-segregation is in some instances a religious requirement.
'Self-identification is also open to abuse by men seeking to access women's spaces and women's bodies,' it said.
'We are already seeing people who were born and still live and present as men claiming that they are trans-women in order to gain access to women's spaces, including convicted sex offenders demanding to be housed in women's prisons; individuals videoing women and girls naked in women's changing rooms; and individuals seeking to join all-women candidate lists in local or national elections.'
It added: 'Allowing self-identification of trans people will enable and embolden these types of activities.'
The Scottish Government recently revealed that the most frequent objection raised by respondents to its consultation on the changes concerned the safety of women and girls.
In a report into the consultation findings, it said that respondents feared 'abuse, exploitation and false declarations' and that women would be put at risk if they had to share toilets, changing rooms, hospital wards and shelters.
'Where respondents explained their concerns, it was often to suggest that the proposal would allow 'any man', 'predatory men' or 'biological men' to gain access to women's spaces where they could pose a potential threat to women's safety,' the Scottish Government report said.