KIEV, Ukraine - Ukraine's jailed and ailing former Prime Minister Yulia Tymoshenko tentatively agreed Friday to have her back condition treated at a local hospital under the supervision of a German doctor.

Tymoshenko lawyer Serhiy Vlasenko said the treatment of Tymoshenko's herniated disc will start Tuesday at a hospital in the eastern city of Kharkiv, where she is jailed. He said she will give her final approval after meeting with her attorneys next week.

Karl Max Einhaeupl, a doctor with Berlin's Charite clinic, who arrived to examine Tymoshenko, said his colleague will observe the treatment.

German Foreign Minister Guido Westerwelle confirmed the treatment deal, saying that it was a positive first step and that talks with the Ukrainian leadership to achieve a sustainable solution will continue.

Tymoshenko, 51, is on a hunger strike to protest the prison's alleged mistreatment of her as she serves a seven-year sentence on charges of abusing her powers when she was prime minister.

Critics have described her case as politically motivated, saying President Viktor Yanukovych, Tymoshenko's rival in the 2010 presidential election, has orchestrated her prosecution. Government officials have denied any claims of bias in the case.

Her case has become a political nightmare for Ukraine, as prominent EU and other officials have been talking about boycotting soccer matches that Ukraine is hosting for the continent's Euro 2012 championships that begin in June.

Tymoshenko's aide Alexander Turchinov on Friday raised alarm about the former premier's health. "She's been on a hunger strike for 15 days," he said. "Her life is in real danger."

Vlasenko said Tymoshenko has visibly lost weight, was drinking only water, and mostly stayed in bed.

Tymoshenko has claimed she was beaten by prison guards and showed bruises. But Viktor Pshonka, Ukrainie's prosecutor-general, told reporters Friday that there are no grounds to assert that she had been beaten.

"We do not rule out that she hurt herself deliberately. We cannot make any conclusion without forensic medical examination, which she did not give consent for," he said.