A Ukrainian human rights official has announced that former prime minister and opposition leader Yulia Tymoshenko is suffering from serious medical problems and should receive treatment outside of prison.

Rights ombudsman Nina Karpacheva said Monday that during her visit to Ms. Tymoshenko at the Kiev prison Sunday, the former prime minister was unable to get out of bed to speak with her.

Karpacheva said the 50-year-old Ms. Tymoshenko needs to be examined and treated outside of prison and should not be interrogated in her cell by investigators.

Last month, Ms. Tymoshenko was sentenced to seven years in prison for exceeding her power as prime minister when she signed a 2009 gas deal with Russia that her opponents say was overly beneficial to Moscow.

The former prime minister has repeatedly denied the charges and described her trial as “a political lynching” aimed at allowing President Viktor Yanukovych to rid himself of a political rival. She had been expected to be the main opposition candidate in a parliamentary election next year, but is not eligible to run if the conviction is upheld. Her lawyers have said they will appeal the verdict.

The United States, the European Union and several rights groups have condemned the charges as politically motivated.

Earlier this month, Ukrainian officials filed additional charges against Ms. Tymoshenko, including embezzlement, theft and tax evasion.

Ukraine's State Tax Administration said Friday that she failed to pay nearly $6 million in taxes when she headed a Ukrainian energy company in the 1990s. It also said that Ms. Tymoshenko concealed $165 million in corporate revenue.