Russia on Saturday faced a storm of international criticism for sentencing three members of the Pussy Riot punk band to two years in prison for a political protest in an Orthodox cathedral.

Speculation mounted that the women, Nadezhda Tolokonnikova, Maria Alyokhina and Yekaterina Samutsevich, could have their sentences reduced on appeal after the damaging global reaction, with the Russian public also questioning the sentence.

Judge Marina Syrova said the three young protesters had shown a 'clear disrespect toward society' by staging a 'Punk Prayer' calling on the Virgin Mary to drive out Vladimir Putin just weeks ahead of his election in March to a third Presidential term.

The United States called the sentences 'disproportionate', while Britain, France and the European Union also said the punishment was excessive and questioned Russia's rights record.

"Putin cronies can jail Pussy Riot but they can't jail their hearts & minds. More proof of Russia tyranny," wrote British rights activist Peter Tatchell on Twitter.

Newspaper owner Alexander Lebedev, who co-owns Russia's Novaya Gazeta daily and owns Britain's Independent daily, on called the women "prisoners of conscience" on his Twitter account.

Russian media and politicians raised the possibility of the women's sentence being reduced.

"There is a feeling that the Moscow city court, after the lawyers' appeal, will cut (the sentence) down to only one year, and after that they will release these foolish women back to their children and loved ones," Komsomolskaya Pravda daily said on Saturday.

Leading ruling party member Andrei Isayev on Friday called the sentence 'harsh' and noted that Putin had yet to speak his full mind on the matter.

Putin had earlier this month said he thought the band members should not be 'judged too severely' while stressing that he strongly disagreed with what they did.

"He has no right to impose his views on the court," Kremlin spokesman Dmitry Peskov told the PublicPost.ru website.

The Russian foreign ministry made no direct comment on Pussy Riot, issuing only a curt statement on Saturday about penalties for offending religious believers in other European countries.

Senior Church members have indicated they would prefer a lighter punishment.

"The whole verdict is based on a very shaky foundation: on the assertion that the punk group members feel hatred towards all Orthodox Christians and Orthodoxy as a whole," reformist priest Andrei Kurayev said on Saturday on his blog.

A senior Orthodox Church council issued a formal statement on Friday calling on the state "to show mercy for the convicted within the framework of the law."

Ordinary Russians also criticised the verdict.

A telephone poll by Moscow Echo liberal radio station on Saturday found 77 percent of listeners considered it "impossible to agree with the verdict."

Moscow police said Saturday that more than 50 protesters detained outside the court on Friday had all been released and some charged with public order offences, the ITAR-TASS news agency reported.

Among those detained was chess champion turned opposition leader Garry Kasparov, who now awaits further questioning, said Alexander Ryklin of the Solidarity political movement led by Kasparov.

"So far there is no charge against him," Ryklin told AFP.

"They have called him in for questioning at the police station on Monday."

Police accused Kasparov of biting an officer on the ear during his detention, Interfax news agency reported on Friday, with Kasparov denying the claim and complaining of being beaten.

British comedian Stephen Fry expressed his fury on Twitter, writing that "Gary Kasparov, the greatest mental athlete ever, (has been) arrested for protesting at the tyrannical 2 years."