KHARKIV, Ukraine (Reuters) - A court in Ukraine on Monday adjourned a trial of jailed former prime minister Yulia Tymoshenko on a new charge of tax evasion until June 25, when the European soccer championship will be under way in the country, for medical reasons.

Tymoshenko is being treated for back trouble in a clinic in the city of Kharkiv near the prison where she is serving a seven-year sentence for abuse-of-office in a case which the West has condemned as politically motivated.

Some European leaders are considering a boycott of Euro-2012 matches in Ukraine in protest against the government's actions over Tymoshenko.

Authorities have ignored calls by the European Union and the United States to release her and opened further charges of large-scale tax evasion and embezzlement in the 1990s when Tymoshenko was head of the gas trader Unified Energy Systems.

Tymoshenko, 51, was unable to attend the resumption of the hearing on these new charges on Monday.

Judge Kostyantyn Sadovsky, adjourning the hearing until June 25, said: "The court rules that it is impossible to consider the case because of the absence of the accused and her counsel."

This will mean the hearing will take place during the June 8-July 1 Euro-2012 European soccer championships which Ukraine is co-hosting with Poland. Kharkiv is one of the four Ukrainian cities where Euro matches will be played, along with Kiev, Lviv and Donetsk.

Ukraine's Specialised Supreme Court on civil and criminal cases is also set to resume hearings into Tymoshenko's appeal against the original abuse-of-office charge for which she is serving a jail sentence.

She has denied all charges in both cases and says they are part of a campaign by President Viktor Yanukovich to destroy the political opposition.

The EU saw Tymoshenko's jailing last October as politically motivated and has said its members will not ratify an association agreement with the former Soviet republic while she is in prison.

European politicians were also alarmed by Tymoshenko's allegations she was beaten by prison guards this month which prison authorities deny. State prosecutors are investigating her complaint.

Tymoshenko was one of the leaders of the 1994 Orange Revolution protests which doomed Yanukovich's first bid for the presidency. She served twice as prime minister before losing the February 2010 presidential election to Yanukovich.

(Additional reporting by Sergiy Karazy; Writing by Richard Balmforth; Editing by Angus MacSwan)