KIEV - Ukrainian ex-prime minister Yulia Tymoshenko exceeded her powers when she ordered state energy firm Naftogaz to sign a gas deal with Russia in 2009, a judge ruled on Tuesday, a verdict set to further strain ties between Ukraine and the West.

State prosecutors have asked the court to sentence Tymoshenko, the main political opponent of President Viktor Yanukovich, to seven years in jail for illegally forcing through the gas deal.

The European Union, one of Ukraine's main trading partners along with Russia, has told Yanukovich, who narrowly beat the charismatic Tymoshenko for the presidency in February 2010, that landmark economic agreements will be in jeopardy if she is jailed.

Judge Rodion Kireyev, who was expected to deliver sentence on the opposition leader later, said Tymoshenko's actions had led to a loss for Naftogaz of 1.5 billion hryvnia ($188 million).

"In January 2009, Tymoshenko Yu. V., exercising the duties of prime minister ... used her powers for criminal ends and, acting deliberately, carried out actions ... which led to heavy consequences," he said.

Even before the judge began reading his verdict, Tymoshenko, who was flanked by her daughter and husband in court, bristled defiance.

"You know very well that the sentence is not being pronounced by Judge Kireyev but by President Yanukovich," she told journalists.  

"Whatever the sentence pronounced, my struggle will continue. This sentence, written by Yanukovich, will not change anything in my life or in my struggle," she said.  

About 2,000 Tymoshenko supporters, scores of police and crowds of anti-Tymoshenko demonstrators who turned out at the behest of the ruling Regions Party had gathered outside the central Kiev court before the verdict was delivered.