The Orthodox Church, dominant in Russia, could be the next in Wales to benefit from EU enlargement.
Romania and Bulgaria joined the EU in January but Britain placed temporary restrictions on people from those countries seeking work in the UK. When the restrictions are lifted, many Orthodox believers could move to Wales.
Archimandrite Deiniol, administrator of the Welsh Orthodox Mission, said Orthodox believers had already increased in Wales, with ethnic Russians from Estonia and Latvia coming to Wales to work in the hospitality sector.
"They come here when they can," said Arch Deiniol, who has a church in Blaenau Ffestiniog.
"They're in the tourism business so they're not free on Sundays, but they come here to see me to keep in contact with the Church."
His service last Christmas was attended by people from 10 countries, eight of them outside the UK.