The United States said Wednesday it was disappointed by Russia's decision to bar an opposition political party from participating in the country's upcoming parliamentary elections.

Secretary of State Hillary Clinton said in a statement that the U.S. also was “troubled” by reports of pressure by authorities against supporters of the Party of People's Freedom, or PARNAS.

Russia's Justice Ministry on Wednesday refused to register PARNAS, a party known for its stance against the nation's powerful prime minister, Vladimir Putin.

Former Russian deputy prime minister and now opposition politician Boris Nemstov told local media the decision to not register PARNAS was a political one.

He said the party would therefore not appeal the decision in court.

Justice Ministry officials defended the decision by saying PARNAS was in violation of several registration procedures.

Clinton said it was “hard to understand” how Wednesday's decision by the Ministry of Justice was consistent with Russia's spoken commitments to free and fair elections.