The Russian Orthodox Church said on Saturday it would respond "in kind and toughly" to the Istanbul-based Ecumenical Patriarchate over Moscow's row with Ukraine's Orthodox Church.

On Thursday a Synod meeting in Istanbul backed Ukraine's request for "autocephalous" - or self-governing - status and reversed the excommunication of Patriarch Filaret, who hopes to lead the newly independent church based in Kiev.

Alexander Volkov, spokesman for Russian Orthodox Patriarch Kirill, said the Holy Synod of the Church would "express its position" on Sunday during a meeting in Minsk, without elaborating on what measures it might take.

Arriving in Minsk, Kirill told reporters: "I hope the Orthodox Church will find the strength to overcome hardships... to stay united."