Top European Union officials are canceling plans to attend events in Ukraine in protest at the imprisonment and treatment of former prime minister Yulia Tymoshenko.

EU Commission President Jose Manuel Barroso announced Monday that he will follow the example of EU Justice Commissioner Viviane Reding, who said she would skip the ceremonial Euro 2012 football (soccer) kick-offs in June.

German Chancellor Angela Merkel has also warned that she may boycott all Euro 2012 matches in Ukraine and expects her ministers to do the same.

The tournament, Europe's most important football championship for national teams, is being co-hosted by Poland and Ukraine from June 8 until July 1.

Also Monday, Czech President Vaclav Klaus cancelled his visit to the summit of Central European heads of state scheduled for May 11 and 12 in Yalta.

Mr. Klaus is the second president to refuse to go to Ukraine for the summit, after German President Joachim Gauck.

Yulia Tymoshenko was sentenced to seven years in prison last year on charges of abuse of office in a 2009 gas deal with Russia. She is now standing trial on tax evasion charges that could extend her prison time to 12 years. Ms. Tymoshenko denies the charges and says they are part of a campaign by President Viktor Yanukovich to remove his strongest political rival.

She has been on a hunger strike for more than a week, after she said she was beaten by prison guards. German doctors diagnosed Ms. Tymoshenko last week with back problems that they say cannot be treated in Ukraine, but the Kyiv government has refused appeals to allow her to leave.