Yulia Tymoshenko, the now-jailed Ukrainian opposition leader on stage with President Viktor Yanukovich at a 2004 political rally in Kiev's Independence Square.

But with Tymoshenko and others in jail, Ukraine's opposition is suffering, leaving Yanukovich hopeful this weekend's parliamentary poll will deliver his Party of Regions a win.

Tymoshenko is serving a seven-year sentence for a 2011 abuse of office conviction.

Opposition supporters have called the trial politically-motivated and in line with a string of criminal probes against senior members of the previous government.

As Yanukovich comes up for re-election as president in 2015 and his party and its allies are seeking to retain a majority in the 450-seat parliament, Tymoshenko's daughter tells Reuters that her mother's incarceration is a political ploy.

(SOUNDBITE) (English) FORMER PRIME MINISTER, YULIA TYMOSHENKO'S DAUGHTERYEVGENIA TYMOSHENKO, SAYING:

"Yanukovich's goal is clear in this situation of my mother's incarceration and repressions. It is clear that he wants his field of not even political activity, but building up of this new dictatorship that he is building to be free of political opponents till the next presidential election. This is very clear that he wants my mother to stay in prison and will do everything possible until 2015."

Tymoshenko was an architect of the 2004 Orange Revolution that robbed Yanukovich of his first bid to the presidency.

She is confined to a hospital for chronic back pain, is under constant surveillance by prison officials and has alleged abuse at their hands.