Lady Gaga has lashed out at Donald Trump and accused the US government of living in an "alternate universe" over reported plans to change how gender is defined.
Mr Trump's administration is said to have drawn up proposals that would see a person's gender defined by the sex listed on their birth certificate, "unless rebutted by reliable genetic evidence".
The controversial move could have profound consequences for transgender and non-binary people.
It would mean they would be unable to change their gender in legal terms later in life.
The proposals would also remove Barack Obama-era protections for transgender people under US civil rights laws in health care, schools and the military.
Gaga suggested Mr Trump was being "driven by ignorance" over the reported policy.
She tweeted: "The government may be living in an alternate universe, but we as a society & culture know who we are and know our truth and must stick together and raise our voices so we can educate them about gender identities.
"While today you might feel unheard or unseen, know that this is not the reality of humanity. This is another display of leadership being driven by ignorance."
She added the hashtags #TransRightsAreHumanRights and #WontBeErased.
Gaga has challenged gender roles publicly through her appearances in the media and music, including her hit single Born This Way.
She has previously spoken of being bisexual and addressed a national equality march in Washington in support of the LGBT movement.
An unreleased memo from the US department for health and human service, containing details of the proposed gender law changes, was first reported by The New York Times.
It states: "The sex listed on a person's birth certificate, as originally issued, shall constitute definitive proof of a person's sex unless rebutted by reliable genetic evidence."
On Monday, Mr Trump said he was "protecting everybody" when he was asked about campaign promises to the LGBT community.
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Around 1.4 million adults identify as transgender in the US, according to a 2016 estimate by the Williams Institute.
Doctors have argued that the law changes would make it impossible to apply to intersex babies who are born with reproductive or sexual anatomy that do not fit conventional categories.