Jailed Ukrainian opposition leader Yulia Tymoshenko has ended her hunger strike and moved to a hospital for treatment for back pains.

President Viktor Yanukovich has faced growing criticism over the conviction of Tymoshenko and the authorities' refusal to let her travel abroad for treatment for chronic back trouble.

Her transfer from prison in the eastern city of Kharkiv to a nearby hospital for treatment, under the supervision of German doctors, was worked out last week in a compromise.

However, it seemed unlikely to relieve pressure on President Yanukovich, who looks increasingly isolated as Ukraine prepares to co-host Europe's biggest soccer tournament.

A number of European Union leaders have threatened to boycott Euro 2012 matches over the issue.

Ukraine has also postponed a summit that was due to take place this week after several leaders decided not to attend.

Ms Tymoshenko, 51, was jailed last October for seven years for alleged abuse of power while in office, a charge she denied.

The former prime minister says she is the victim of a vendetta by Mr Yanukovich, who narrowly beat her for the presidency in February 2010.

The European Union and the United States have condemned her trial and sentencing as politically motivated and want her released.

Outcry in the West intensified after Tymoshenko said she had been beaten in jail and went on hunger strike on 20 April in protest against alleged ill-treatment.

Authorities deny she was mistreated.

German doctor Lutz Harms of Berlin's Charite hospital, who is supervising her treatment, said she ended her hunger strike after being admitted to the Kharkiv clinic this morning.

"We have begun to start a normal process of feeding," he told reporters.