Polish President Bronislaw Komorowski has urged Ukraine to resolve the imprisonment of former prime minister Yulia Tymoshenko, saying Kyiv's bid to join the European Union hinges on it.

Mr. Komorowski said Monday a realistic solution must be found if Ukraine wants to continue integration with the EU. The visiting Polish leader, whose country currently holds the rotating EU presidency, spoke to reporters in Kyiv.

Ms. Tymoshenko was convicted and sentenced to seven years in prison last month 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.

Concerns about her health have grown since her conviction, with reports that she is suffering from serious medical problems, including severe back pain.

Ukrainian President Viktor Yanukovych said Monday he has instructed authorities to provide Ms. Tymoshenko with medical care and attention that meet “European” standards.

The 51-year-old former prime minister has denied the charges against her and has described her trial as “a political lynching” aimed at allowing President 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 human rights groups have condemned the charges against Ms. Tymoshenko as politically motivated.