London ( CNN ) -- Music stars including Pete Townshend of The Who , Alex Kapranos of Franz Ferdinand and Corinne Bailey Rae called on Russia to free three members of the punk rock band Pussy Riot , who are on trial in Moscow on hooliganism charges . The musicians said the charge was `` preposterous , '' arguing that artists `` make legitimate political protest and fight for freedom of speech . '' The Pussy Riot members went on trial Monday , charged with hooliganism after performing a song criticizing President Vladimir Putin in one of Moscow 's grandest cathedrals , Russia 's state news agency reported . `` Mother Mary please drive Putin away , '' the band screamed , their faces covered in neon masks , inside Christ Savior Cathedral in February . Three were arrested soon after . The charge carries a potential seven-year sentence . Putin is visiting London on Thursday , Pussy Riot 's celebrity backers noted as they urged him to `` ensure these three women receive a fair trial . '' `` We are especially concerned about recent reports that food is being withheld from them and that they have appeared in court in a cage , '' their supporters said in a letter to the Times of London . Nadezhda Tolokonnikova , 23 , Maria Alyokhina , 24 , and Yekaterina Samutsevich , 29 , grinned at cameras and waved their handcuffed arms behind their backs Monday as police brought them from a van into the court . They appeared in court in an enclosure that forced them to bend down to speak through small window to be heard . The women apologized to Orthodox Christian believers if they felt they had been insulted , state news agency RIA-Novosti reported . The trial is taking place at the Khamovnichesky Court , the agency said . Read more : Jailed punk band Pussy Riot pushes free speech limits in Russia . Amnesty International said Monday the trial `` never should have taken place . '' John Dalhuisen of Amnesty said the singers had been making `` a legitimate protest -- this is not a criminal offense . They must be released immediately . '' `` They dared to attack the two pillars of modern Russian establishment -- the Kremlin and the Orthodox Church . While many may have found their act offensive , the sentence of up to seven years in prison they may expect on the charges of hooliganism is wildly out of all proportion , '' he said . Pussy Riot specializes in sudden , often illegal public performances , including one in Moscow 's Red Square . The punk prayer was inspired by the women 's anger about the relationship between the Russian government and the Orthodox Church , according to their manager , Tolokonnikova 's husband . The Orthodox leader Patriarch Kyril has been widely reported as saying Putin 's years in power have been a miracle from God . The band 's behavior in one of Russia 's most sacred cathedrals has outraged many of the country 's faithful . `` This is a disgusting thing to do , '' one woman told CNN . `` They should go to jail , '' said another . `` A year or two . Let them think about their behavior . '' But even some of those who were offended believe the women should not be in jail . `` If necessary , God will punish them , '' said one man . `` It must be not be cruel punishment . '' CNN 's Phil Black and Alla Eshchenko contributed to this report .
Three members of Pussy Riot are on trial , facing a potential seven - year sentence . They perform an anti - Putin concert in London 's Christ Savior Cathedral . Alex Kapranos of Franz Ferdinand and Pete Townshend of The Who want them set free . Their open letter comes as Vladimir Putin visits London .