Tymoshenko, a leader of the country's Orange Revolution in 2005, is serving a seven year prison term after being convicted of charges she abused her authority in a 2009 gas deal with Russian energy company Gazprom.
Her legal team asked the country's high court to dismiss the charges because of a lack of evidence. Her political supporters, including Western governments, say the charges against her are politically motivated.
Although a judge in the case said there were no grounds for an appeal, Tymoshenko's lawyer, Serhiy Vlasenko, said Wednesday he was ready with another challenge.
"Literally by the end of this week we will complete an addition to the appeal concerning the lack of justice for Yulia Tymoshenko in Ukraine and hand it over to the European Court of Human Rights," he was quoted by Russia's state-run news agency RIA Novosti as saying.
Vlasenko said the court's decision was influenced by Ukrainian President Viktor Yanukovych. Tymoshenko lost to Yanukovych in a brutal 2010 campaign.
British Minister for Europe David Lidington said he was disappointed with the verdict, calling on Kiev to end a practice of selective justice.
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