Laws recently introduced in the rebel-held Luhansk region affectively outlaw Protestant Christianity, the Kharkiv Human Rights Protection Group has warned.
The organisation alleges that officials in the territory, which has been controlled by pro-Russian separatists since 2014, have imposed a re-registration process for churches.
Ukraine's Institute for Religious Freedom reports that evangelical Christian communities have been barred from re-registration, meaning they are breaking the law if they do not cease to operate.
The Christian ministry Ellel Ministries, which trains church leaders across eastern Europe said it was monitoring the situation and liaising with colleagues in the country.
Staff member, Richard Jones (whose real name has been protected for security reasons), told Premier the legislation forms part of a pro-Russian agenda endorsed by Moscow.
Mr Jones said: "Russia is encouraging this kind of thing to happen, to make sure that there is a completely pro-Russian area surrounding the Russian Federation."
"They make it impossible for any churches to re-register which means, of course, the churches can no longer operate even in their own buildings.
Human rights advocates claim all non-Russian Orthodox churches are facing persecution in Luhansk and neighbouring Donetsk, which is also in the hands of separatists.
Mr Jones, who has travelled extensively in Russia and Ukraine, added: "We pray for our fellow believers there because they are going through a very strongly oppressed time, just as believers are in China, for example.
Click here to listen to Premier's Alex Williams speaking with Richard Jones at Ellel Ministries:
Top picture: A Greek Catholic church in Luhansk
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