Speaking to The Daily Telegraph during a visit to London yesterday, the Ukrainian foreign minister, Leonid Kozhara, said there was no plan to release the ex-prime minister, Yulia Tymoshenko, before an EU deadline at the end of this month.
Ms Tymoshenko, 52, who helped lead the mass street protests that felled the country's authoritarian government in 2004, was jailed in 2011 over her handling of a major gas deal with Russia that prosecutors claim saddled Ukraine with crippling gas charges.
Critics say she was framed to force her out of politics, and that she should be freed as part of a package of legal reforms that the EU wants Ukraine to carry out before the free trade deal is signed.
The deadline for carrying out the reforms is the end of this month.
However, Mr Kozhara insisted that the court's decision was final, and that it was not for the Ukrainian government to interfere with the "rule of law".
"Millions of people in the Ukraine truly believe that former prime minister was rightly convicted," he said.
"She (Ms Tymoshenko) did big damage to our economy, and overstepped the law."
"We accept that the Tymoshenko case is a problem in our relationship with the EU, but it is our strong opinion that a single criminal case should not overwhelm our relationship."
Mr Kozhara's uncompromising stance threatens to expose divisions among European nations over how tough a line to take with Ukraine over Ms Tymoshenko's seven-year imprisonment, which she says was the result of a "Stalinist" show trial.
Last summer, ministers from Britain, France and Germany boycotted official attendances of the early stages of the Euro 2012 football tournament in Ukraine, citing "widespread concerns about about selective justice and the rule of law".
But there is limited appetite for letting the matter prevent Ukraine signing the association agreement and free trade pact, partly because of fears that it would drive the former Soviet republic further back into Russia's sphere of influence.
Poland and Sweden have already made it clear that they want the agreement to be signed, while British diplomats are understood to believe it should not be a sticking point other.
Hampering Europe's ability to maintain a united stance is the ongoing argument about whether Ms Tymoshenko is quite as innocent as her supporters claims.
Challenging her image in the West as the blonde-haired heroine of the 2004 pro-democracy protests, Mr Kozhara claimed that she had signed a gas deal favourable to Moscow in 2009 in order to win the Kremlin's backing for her own presidential bid in 2010.
The deal, he alleged, had led to Ukraine paying $6 billion a year more than it should for its gas supplies from Russia - or the equivalent of 100 euros a year for every Ukrainian citizen.
"She deliberately acted while having a strong personal conflict of interests," he said.
British diplomats are understood to share the belief that there may have been a legitimate case against Ms Tymoshenko.
However, they also contend that she is most likely the victim of selective prosecution, and that in a country known for high-levels of official corruption, many other officials should also be in the dock as well.
Mr Kozhara said that as a condition of the free trade agreement, Ukraine was introducing widespread reforms to improve both the judiciary and police.
Source: The Daily Telegraph