Washington DC - A US federal judge has blocked prison officials from transferring a dozen incarcerated trans women to men's facilities, going against an executive order issued by President Donald Trump.

Trump had launched an all out war on diversity programs and LGBTQ+ rights following his inauguration in January, notably ordering authorities to ensure that "males are not detained in women's prisons."

Incarcerated trans women filed a lawsuit in a bid to prevent the government from implementing the order because they were concerned they would lose their gender-related medical treatment.

US District Judge Royce Lamberth issued an injunction this month to stop the transfer of three women and extended it to nine others on Monday.

Donald Trump Trump's press secretary gives shock update on Ukraine deal timeline

"The same reasoning from the Court's original TRO Order [ECF No. 23] still applies, with nothing in the record to compel a different outcome," Lamberth said in the ruling seen by AFP.

He cited the Eighth Amendment, which bars cruel and unusual punishment, in his decision.

"Summarily removing the possibility of housing the plaintiffs in a women's facility, when that was determined to be the appropriate facility under the existing constitutional and statutory regime, demonstrates a likelihood of success on the merits of the plaintiffs' Eighth Amendment claim," he said.

Trump has demonized any recognition of gender diversity since his return to power, attacking transgender people – a small minority of the population – and gender-affirming care for minors in both his rhetoric and in executive orders, which are the subject of multiple legal challenges.