KIEV - International pressure mounted on Ukraine on Thursday over its treatment of jailed opposition leader Yulia Tymoshenko, but Kiev warned that any boycott of the European football championship next month would only hurt the interests of football fans.

Nine European leaders are shunning a Central European summit hosted by the former Soviet republic this month in a show of displeasure at Tymoshenko's plight which the West says highlights a decline in democratic values in the country.

The move appeared to foreshadow similar action by European politicians at the Euro-2012 football championship, which Ukraine is co-hosting with Poland in June and July and which it hopes will be a showcase for the country as a modern European nation.

The presidents of Germany, Austria, Italy, Croatia, Estonia, Slovenia, Bulgaria and the Czech Republic have all said they would not attend the May 11-12 gathering in the Black Sea resort of Yalta to be hosted by President Viktor Yanukovich.

European Commission President Jose Manuel Barroso has said he had no plans to visit Ukraine because of Tymoshenko who says she was jailed on Yanukovich's order and fears for her life.

The delegation of the European Union to Ukraine said on Thursday the other 26 commissioners would follow a similar line.

The boycott of the informal summit, which was held in Poland last year and attracted 20 heads of states, risks embarrassing Kiev which says it wants eventually to join the European Union.

The snubbing of the summit could be a precursor to an even more painful boycott of the Euro tournament which Ukraine hopes would cement its position in the European mainstream.

Ukraine's Foreign Ministry said on Thursday that attempts to politicise the Euro tournament were "destructive".

"A successful championship will be a victory not for politicians, parties or ideologies, but for all Ukrainians and Poles. Its failure will be a loss for millions ...", it said.

Tymoshenko, a former prime minister and Yanukovich's main political rival, was sentenced to seven years in prison last October for abuse of office after a trial that the West says was politically motivated.

Western politicians reacted with horror last week after she alleged she had been beaten in prison.

She is held in a prison in the city of Kharkiv, one of the Euro-2012 venues and has been on a hunger strike since April 20 in protest at what she said was an assault by prison guards, an allegation denied by the prison administration.

In Poland, the issue prompted a domestic political dispute on Thursday as the main opposition party urged a boycott of matches held in Ukraine while President Bronislaw Komorowski and Prime Minister Donald Tusk spoke against such steps.

Yet, Tusk warned Ukraine its reputation would "suffer dramatically" if no humanitarian solution were found.

"I have left Ukraine's prime minister and president in no doubt that the (Tymoshenko) case ...is a test of credibility for the present Ukrainian authorities and that the reputation of Ukraine would suffer dramatically if it does not find a solution that we deem civilised before the European championship," he said.

Russian Prime Minister and president-elect Vladimir Putin also spoke out against a boycott.

"I think that under no circumstances should one mix politics, business and other issues with sports," Itar-Tass news agency quoted Putin as saying. "One should leave sports alone."

Matches between 16 European teams will be held in Ukraine and Poland in June leading up to the final in Kiev on July 1.

Tymoshenko, 51, was one of the leaders of the 2004 Orange Revolution that derailed Yanukovich's first bid for presidency.

Her family says she is in poor health due to the hunger strike and chronic back pain but Tymoshenko refuses treatment, saying she does not trust state-appointed doctors.

A Foreign Ministry spokesman reacted angrily to news that German Chancellor Angela Merkel would not attend the Euro championship, calling the move a return to Cold War tactics.

The Ukrainian government and businessmen have invested billions of dollars in preparations for the biggest sports event during Yanukovich's current term in office.

But the government has shown no signs of heeding Brussels' calls for Tymoshenko to be freed. State prosecutors have, instead, brought to court fresh tax evasion charges against her which carry a sentence of up to 12 years.

The EU has warned Ukraine its members will not ratify milestone bilateral agreements on political association and free trade as long as Tymoshenko remains in prison.

"These (boycott moves) are the first steps towards international isolation, not for Ukraine but for Yanukovich personally," said Kiev-based political analyst Ihor Zhdanov.

"This will go on for as long as Tymoshenko remains in prison. But one must understand that Tymoshenko simply exemplifies all the problems with democracy in Ukraine." (Reuters)