Russian feminist punk band Pussy Riot, two of whose alleged members face up to seven years in jail for a "punk prayer" they staged in Moscow's main cathedral, have received unexpected backing from a group of Orthodox Christians who say they are being too harshly punished.

The group's performances have seen them appear in masks in a range of unexpected places to sing anti-government songs.

Part of the growing protest movement against Vladimir Putin, who was elected to a third term last Sunday, the group sang an obscenity-strewn song in Christ the Cathedral Saviour last month, including an appeal to the "Holy Mother, Blessed Virgin," asking her to "chase Putin out".

The Russian Orthodox Church condemned the stunt and called for the group to be punished. Days after the performance the group's alleged members were arrested and two, Maria Alyokhina and Nadezhda Tolokonnikova, have been charged with hooliganism. The pair, both of whom have young daughters, have been refused bail. Neither has admitted being part of the group.

Lina Moniava, a charity worker and Orthodox Christian, sent a petition to the head of the church appealing for them to ask for the criminal case to be closed. What the group did was "intolerable" said the letter, but "what is more intolerable is the reaction to the events".

One of the anti-Putin movement's leaders, Alexei Navalny, also called for the women to be released, saying the act was "idiotic" but that they were not dangerous. Pussy Riot performed a concert on the roof of the detention centre where Navalny was held after the first large protest in December and Navalny, also an Orthodox Christian, held a one-person picket outside police headquarters in Moscow, where the women are being held, last week.

There was plenty of support for the jailed pair at yesterday's opposition rally in Moscow, which saw up to 15,000 gather in the city centre.

"Pussy vs Putin" said one sign in English at the demonstration while another called for "Pussy Riot for the Eurovision". One protester held up the female torso of a shop dummy with "Free Pussy Riot" written on the back. The two women were included in a list of political prisoners read out from the stage.