KIEV, Ukraine - Facing deepening Western criticism, Ukraine's president on Thursday ordered a thorough probe into the alleged beating by prison officials of jailed former Prime Minister Yulia Tymoshenko.

Tymoshenko, 51, the country's top opposition leader, launched a hunger strike nearly a week ago to protest the alleged violence. She claims that prison guards punched her in the stomach and twisted her arms and legs while transporting her to a hospital against her will to be treated for a spinal condition. Tymoshenko was soon returned to jail after refusing treatment from state doctors.

Ukrainian President Viktor Yanukovych made his statement about Tymoshenko on Thursday, hours after German President Joachim Gauck canceled a visit to Ukraine next month and opposition politicians in Germany urged their government to boycott the Euro 2012 football championship in Ukraine in June.

The European Union's Justice Commissioner Viviane Reding, meanwhile, canceled her planned attendance at the Euro 2012's opening match to protest the human-rights situation in Ukraine, her office in Brussels said.

EU foreign policy chief Catherine Ashton also said Thursday that she is "deeply preoccupied" by what is happening to Tymoshenko and called on Ukraine's government to properly examine her complaints. Ashton asked that the EU ambassador in Ukraine be allowed to visit Tymoshenko in prison.

In Kiev, however, some observers doubted whether Yanukovych was sincere in his instructions to prosecutors to investigate the handling of Tymoshenko, since an investigation was conducted this week and prosecutors concluded Tymoshenko was not abused.

Tymoshenko is serving a seven-year prison term on charges of abusing her powers during negotiations about gas supplies with Russia. The West has strongly condemned the verdict as politically motivated and threatened to freeze cooperation with Ukraine.

Tymoshenko denies the charges, saying they are part of a campaign by Yanukovych, her longtime foe, to bar her from politics. Yanukovych has denied involvement in the Tymoshenko case and said the investigations against her are part of an anticorruption effort.

The opposition leader has a severe spinal condition, and a group of German doctors who examined her said she needs urgent treatment at a specialized clinic.