KIEV, Ukraine — The European Union Ambassador to Ukraine has been prevented from visiting former Ukrainian premier Yulia Tymoshenko in a hospital where she is being treated.

Tymoshenko, 51, the country's top opposition leader, is serving a seven-year sentence on charges of abuse of office that have been condemned as politically motivated by the West. She is being treated for a spinal condition in a clinic in the eastern Ukrainian city of Kharkiv where her prison is located.

On Sunday, security guards outside Tymoshenko's hospital ward prevented the EU ambassador, Jose Manuel Pinto Teixeira, from entering, saying he lacked required special permission from prison authorities. Very few foreign officials have been able to visit Tymoshenko since her jailing in October.