AMNESTY International is calling for the immediate release of three members of a Russian feminist punk band who face up to seven years in prison for performing in a church.

The global human rights watchdog said it did not know if the detained women were in fact members of the Pussy Riot band because the group performed all its protest songs wearing balaclavas.

"Even if the three arrested women did take part in the protest, the severity of the response of the Russian authorities... would not be a justifiable response to the peaceful - if, to many, offensive - expression of their political beliefs," Amnesty International said yesterday. "They would therefore be prisoners of conscience."

Five members of the radical group climbed on the altar of Moscow's Christ the Saviour Cathedral - the country's central place of worship - on February 21 and sang a song they called a Punk Prayer before being seized by guards.

The song's lyrics called for the Virgin Mary to "drive out (president-elect Vladimir) Putin" and to "become a feminist".

The action drew a furious response from the increasingly powerful Russian Orthodox Church. Patriarch Kirill called the stunt "blasphemous" and criticised all supporters of the group.

The three women have been charged with hooliganism committed by an organised group - an unusually harsh charge for protesters.

They are being held in pre-trial detention until late April even though two of them have small children.

The stunt has divided public opinion in a country where some 70 per cent describe themselves as Orthodox Christian.

Mr Putin's spokesman Dmitry Peskov has told the private Dozhd (Rain) television channel that the Russian leader had a "negative" opinion of the group.