The Istanbul Convention, signed by 45 countries and the EU, requires governments to adopt legislation prosecuting domestic violence and similar abuse.
Aside from Turkey, the treaty had so far only been ratified by 34 countries.
But Turkey now says the treaty – which seeks to prevent, prosecute and eliminate domestic violence – was incompatible with its family values because it has been “hijacked” by people trying to “normalise homosexuality”.
In a move which sparked large protests by Turkish women, President Recep Tayyip Erdogan’s government unilaterally quit the convention on Saturday, nearly 10 years after it became the first signatory to the landmark agreement.
Women’s rights activists say the Istanbul Convention was crucial to combating domestic violence in Turkey.
On Sunday, US President Joe Biden issued a statement to express his disappointment, joining a growing chorus of criticism.
“Around the world, we are seeing increases in the number of domestic violence incidents, including reports of rising femicide in Turkey,” he said.
“Countries should be working to strengthen and renew their commitments to ending violence against women, not rejecting international treaties designed to protect women and hold abusers accountable. Turkey’s move is a disheartening step backward.”
The EU’s foreign policy chief, Josep Borrell, said Turkey was sending “a dangerous message across the world” about the rights of women.
In a tweet, European Commission president Ursula von der Leyen wrote: “Women deserve a strong legal framework to protect them.”
Marija Pejcinovic Buric, the head of Europe’s top human rights body, the Council of Europe, said, “This move is a huge setback and all the more deplorable because it compromises the protection of women in Turkey, across Europe and beyond.”
Erdogan’s office issued a statement explaining its decision.
“The Istanbul Convention, originally intended to promote women’s rights, was hijacked by a group of people attempting to normalise homosexuality – which is incompatible with Turkey’s social and family values. Hence the decision to withdraw,” the statement said, without giving further details.
It said Turkey was not the only country that had “serious concerns” about the Istanbul Convention.
Critics of the accord said it was being used to advocate for greater acceptance of the LGBT community and lifestyles in Turkey.
At least 300 women were murdered in the country last year, according to Turkey’s We Will Stop Femicide Platform.
However, the group said the number could be even greater, as dozens more women were found dead in suspicious circumstances.