Ukraine's jailed ex-premier Yulia Tymoshenko on Thursday urged the nation to oust President Viktor Yanukovych's "mafia" in upcoming parliamentary polls, as the EU and US issued a rare joint call for clean elections. The nation of 46 million is heading into Sunday's elections amid Western outrage at opposition leader Tymoshenko's seven-year jail sentence on abuse of office charges that some have decried as politically motivated. Tymoshenko's daughter in Kiev read an emotional letter from her detained mother calling on Ukrainians "not to cast a single vote" for Yanukovych's ruling Regions Party. "You are smart and intelligent people. Do not pay attention to the smear campaigns being waged against the unified opposition," Yevgenia Tymoshenko read in a shaking voice. "Chasing this mafia from power is not only the task of the opposition. It is a war against dictatorship and against injustice that requires the mobilisation of each of you," the letter added. The bloc that includes Tymoshenko's party is currently running joint second in opinion polls with the new UDAR (Punch) group of boxing superstar Vitali Klitschko. Her conviction prevents the firebrand Tymoshenko from standing for parliament in the ballot. But her image is far from forgotten: Tymoshenko's voice still features in advertising and her trademark blond braid is a regular feature of opposition campaign posters. Tymoshenko and Klitschko's parties have more recently forged a loose alliance and could become the largest coalition in the new parliament, should they recruit a few more independents. Yanukovych's party has made repeated recent pledges to stage a fair ballot, as it faces criticism that it waged a campaign against Tymoshenko that was politically motivated and ultimately aimed at removing her from the vote. "It is very important to have transparent elections," Regions Party member Olexander Yefremov said. "We understand that and we will do our best to make that a reality." His comments came as US Secretary of State Hillary Clinton and top EU diplomat Catherine Ashton published an extremely rare joint appeal on the eve of the vote, calling on Yanukovych to prove his democratic credentials. "We are concerned about reports of the use of administrative resources to favour ruling party candidates and the difficulties several media outlets face," they said in a joint piece published in the International Herald Tribune newspaper. "Important steps now have to be taken by the Ukrainian government to fulfil its full potential," the joint letter says. Klitschko for his part has been running a hectic schedule that has seen his towering figure appear at two or three different campaign events around Kiev every evening. Late Thursday, the heavyweight champion turned up at a football stadium on the edge of Kiev for a campaign event to support one of his party's local outsiders. About 200 people, most of them elderly women, urged Klitschko to run for president in 2015 polls and root out corruption in parliament in the meantime. "Watching them fight corruption makes you well up with tears," the 41-year-old said of the authorities as his supporters crowded into a corner of the Kolos stadium. "They do not fight corruption -- they live with it. They make it feel at home." Klitschko insisted he was concentrating on the parliamentary polls even as his adoring fans urged him to take on Yanukovych in 2015. "As of today, the people's support is pushing us into the Rada," Klitschko said, referring to Ukraine's parliament known as the Verkhovna Rada, as chants of "President!" echoed in the crowd. "That is what we are working towards today," Klitschko said.