Prime Minister Yuliya Tymoshenko's campaign chief accuses rival's supporters of murder in Ivano Frankivsk Oblast. (AP) Ukrainian Prime Minister Yulia Tymoshenko's presidential campaign chief has accused her rival's supporters of killing a member of her campaign staff in the early hours of election day.

Alexander Turchinov says supporters of rival candidate Viktor Yanukovych killed a Tymoshenko staffer who was at a voting station in Ivano-Frankivsk — a Tymoshenko stronghold in western Ukraine.

Police in Ivano-Frankivsk confirmed the death, but said they had yet to establish the cause of death.

Yanukovych's spokesman declined immediate comment on the accusations.

Ukrainians are voting Sunday to pick between Tymoshenko and Yanukovych in a bitterly contested presidential election.