Ukrainian President Petro Poroshenko has signed a law requiring the Ukrainian Orthodox Church of the Moscow Patriarchate (UOC-MP) to change its name to one that reveals its affiliation with the Moscow-based Russian Orthodox Church.
The law signed on December 22 requires the UOC-MP to make its link to the Moscow patriarch explicit.
The new law was the latest development in Ukraine's quest to create its own, independent Orthodox Church.
In October, Ecumenical Patriarch Bartholomew I of Constantinople revoked a centuries-old ruling placing Ukraine's Orthodox Church under the Moscow patriarch.
In response, the Russian Orthodox Church broke off relations with the ecumenical patriarch.
Religious leaders in Ukraine held a synod last week and agreed to establish a new Orthodox national church that is independent of Russia.
Poroshenko said the new law would make it easier for Orthodox believers to make a choice between the new church and the Russian-affiliated one.
"It is easier to make a choice when all things are called by their names," he said.
The UOC-MP actively opposed the measure, saying it was a violation of freedom of religion and an example of unconstitutional state interference in religious affairs.
More than 1,000 priests and believers of the UOC-MP protested outside the legislature on December 20.
The Moscow Patriarchate has opposed the creation of a new Orthodox Church in Ukraine, saying it would lead to sectarian violence.
Relations between Russia and Ukraine have been frayed since Moscow occupied and annexed the Ukrainian region of Crimea in 2014 and began providing military, economic, and political support to separatist formations in eastern Ukraine.
More than 10,300 people have been killed in the conflict in eastern Ukraine since early 2014.
Although Moscow denies interfering in Ukraine's domestic affairs, the International Criminal Court in November 2016 ruled that the fighting in eastern Ukraine was "an international armed conflict between Ukraine and the Russian Federation."