Russian judges who upheld the prison sentences of two of the three members of the all-female punk band Pussy Riot have defended their decision, saying it was made independently and without pressure.

An appeals court on Wednesday sentenced Nadezhda Tolokonnikova and Maria Alekhina to two years in a prison camp for an unsanctioned protest at a Moscow cathedral. But the court released their bandmate, Yekaterina Samutsevich, after handing her a suspended sentence, saying she was thrown out of the cathedral by guards before she could take part in the performance.

Judge Larisa Polyakova, in a highly unusual move, held a news conference Thursday, saying the behavior of Tolokonnikova and Alekhina could not be “corrected” unless they were isolated from society. She denied that the judges arrived at their decision under any pressure from the Kremlin, and said they followed the law.

Samutsevich, in an interview with Russia's REN-TV , said the case had been misrepresented by Russian state television and accused authorities of carrying out a “calculated campaign” of harassment.

All three women were convicted in August of hooliganism motivated by religious hatred. They argued in court on Wednesday that their impromptu performance was political in nature and not an attack on religion.

The trio was arrested on the altar of Russia's most prominent Orthodox cathedral in January, after they called on the Virgin Mary to deliver them from Russian President Vladimir Putin.

Amnesty International on Wednesday called the decision by the court “half-hearted,” saying any decision that shortens the wrongful detention of the three women is welcome but that justice was not done Wednesday. The rights group said the government has introduced numerous new restrictions to freedom of expression in recent months, and the women should not have been prosecuted in the first place.

Russian Prime Minister Dmitry Medvedev has said he thought the punishment was very strict. But President Putin recently said the court ruling was correct.