Ukrainian churches are facing closure after a government clampdown restricting how churches can operate.

Local leaders in the eastern Luhansk region, which is controlled by Russian separatists, passed a law which restricts how churches in the area can operate, according to the Slavic Gospel Association.

'Basically [it] forbids the churches to conduct worship, hold small groups, or meetings in homes. And also, it looks like they're going to require each religious organisation to obtain a new registration by August,' Slavic Gospel Association's Joel Griffith said.

It means that churches will be considered illegal unless they can show they have at least 30 memoers living within a specific area. It also restricts how churches operate outside their walls.

'Apparently, distribution of religious literature, even among churches, is prohibited without personal written permission of the authorities,' Griffith said. 'It also appears the distribution outside of the churches isn't even really referenced in the law. So, that's kind of a question mark.'

He added that church leaders in Eastern Ukraine are concerned the law could be used to blame churches for extremist or terrorist activity and espionage.

'Certainly, I know that they're going to do all that they can in obedience to Christ. He is their first concern there. And they're going to go ahead and proclaim the Gospel, no matter what happens,' said Griffith. 'They're just going to have to adopt [a way] they can best do it discreetly.'