ISTANBUL — U.S. President Joe Biden has called Turkey's abandonment of an international agreement aimed at preventing violence against women "deeply disappointing."

In a White House statement posted Sunday, Biden said Turkey's withdrawal from the Istanbul Convention was "sudden and unwarranted."

"This is a disheartening step backward for the international movement to end violence against women globally," Biden said.

Turkish President Recep Tayyip Erdogan ended Turkey's participation in the Council of Europe agreement through an overnight decree issued early Saturday. The move was a blow to the country's women's rights movement, which says domestic violence and femicide are on the rise.

Biden's statement comes at a time of uncertain Turkish-American relations. He and Erdogan have not spoken on the phone since Biden took office in January. 

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

Turkey was the first nation to sign the agreement, which carries the name of its largest city. 

The European Union's foreign policy chief, Josep Borrell, called late Saturday for Turkey to rejoin the pact. 

"Now is the time to show leadership and enhance global efforts to fight violence against women and girls, not to retreat. This is why we cannot but regret deeply and express incomprehension towards the decision of the Turkish government to withdraw from this convention that even bears the name of Istanbul," Borrell said.