ISTANBUL — Turkey has withdrawn from a landmark European treaty protecting women from violence that it was the first to sign 10 years ago and that bears the name of its largest city. 

President Recep Tayyip Erdogan's decree early Saturday annulling Turkey's ratification of the Istanbul Convention is a blow to women's rights advocates, who say the agreement is crucial to combating domestic violence. 

The Council of Europe's Secretary General, Marija Pejčinović Burić, called the decision "devastating." 

"This move is a huge setback to these efforts and all the more deplorable because it compromises the protection of women in Turkey, across Europe and beyond," she said. 

The Istanbul Convention states that men and women have equal rights and obliges state authorities to take steps to prevent gender-based violence against women, protect victims and prosecute perpetrators.

Some officials from Erdogan's Islam-oriented party have advocated a review of the agreement, arguing it encourages divorce and undermines the traditional family, which they say are contrary to the country's conservative values. 

Critics also claim the treaty promotes homosexuality through the use of categories like gender, sexual orientation and gender identity. They see that as a threat to Turkish families. Hate speech has been on the rise in Turkey, including the interior minister who described LGBT people as "perverts" in a tweet. Erdogan has rejected their existence altogether. 

Women's groups and their allies who have been protesting to keep the convention intact immediately called for demonstrations across the country Saturday under the slogan "Withdraw the decision, implement the treaty." They said their years-long struggle would not be erased in one night. 

Rights groups say violence against and killing of women is on the rise in Turkey but the interior minister called that a "complete lie" on Saturday. 

A total of 77 women have been killed since the start of the year, according to the We Will Stop Femicide Platform. Some 409 women were killed in 2020, with dozens found dead under suspicious circumstances, according to the group. 

Advocacy group Women's Coalition Turkey said the withdrawal from a human rights agreement was a first in Turkey. "It is clear that this decision will further encourage the murderers of women, harassers, rapists," their statement said. 

Turkey's minister for family, labor and social policies tweeted that women's rights are still protected by Turkish laws and the judicial system is "dynamic and strong enough" to enact new regulations. Zehra Zumrut Selcuk also tweeted the government would continue to have "zero tolerance" for violence against women. 

Erdogan has repeatedly stressed the "holiness" of the family and called on women to have three children. His communications director, Fahrettin Altun, said the government's motto was 'Powerful Families, Powerful Society." 

Many women suffer physical or sexual violence at the hands of their husbands or partners, but up-to-date official statistics are unavailable. The Istanbul Convention requires states to collect data. 

Protesting women is Istanbul shouted "you cannot lock millions of women to their homes, you cannot erase them from the streets and the squares."

Turkey was the first country to sign the Council of Europe's "Convention on preventing and combating violence against women and domestic violence" at a committee of ministers meeting in Istanbul in 2011. The law came into force in 2014 and Turkey's constitution says international agreements have the force of law. 

Some lawyers claimed Saturday that the treaty is still active, arguing the president cannot withdraw from it without the approval of parliament, which ratified it in 2012.

But Erdogan gained sweeping powers with his re-election in 2018, setting in motion the change in Turkey from a parliamentary system to an executive presidency.

Women lawmakers from Turkey's main opposition party said they will not recognize the decree and called it another "coup" on parliament, which had unanimously accepted the treaty, and a usurpation of the rights of 42 million women.