Ukraine's high court on Wednesday upheld former Prime Minister Yulia Tymoshenko's conviction and seven-year jail sentence for abuse of power linked to a disputed 2009 gas deal with Russia.

"The judicial panel has ruled that the appeal filed by Tymoshenko is not subject to approval," Judge Olexander Elfimov told the court.

The International Monetary Fund again urged Ukraine Friday to raise gas prices for consumers, a sticking point in the resumption of an IMF bailout.

Ukraine's strong economic recovery in 2010-2011, following a global crisis, was slowing under pressure from lower demand for its exports and slow credit growth, the IMF said in an annual review of the economy.

Several hundred opponents of a law elevating the status of Russian in Ukraine camped out in Kiev on Thursday and several pressed on with hunger strikes as political tensions soared over the contentious issue.

The sit-in outside a conference center in the capital Kiev follows Wednesday's violent clashes between around a thousand protesters and police triggered by the rushed passing by parliament, the Verkhovna Rada, of the law the day earlier.

Ukraine police on Wednesday used tear gas and several people were injured at a chaotic protest against a new language law as the president summoned the leaders of parliament to limit a growing crisis.

The opposition has reacted furiously to the rushed passing by the Ukrainian parliament the Verkhovna Rada late on Tuesday of the law elevating the status of Russian, which was not on the parliament's agenda for that day.

The legal problems of Ukraine's jailed former Prime Minister Yulia Tymoshenko mounted on Tuesday after a top prosecutor said he was planning to charge her over the murder of a deputy in 1996.

Deputy Prosecutor General Renat Kuzmin said in a newspaper interview the only obstacle in the way of charging was Tymoshenko's current hospitalization for severe back pains but expressed confidence the case would come to court.

A German doctor who has examined Ukraine's jailed ex-premier Yulia Tymoshenko said Tuesday that he doubted she could ever recover from serious spinal problems with the care she is receiving.

Karl Max Einhaeupl, head of Berlin's Charite hospital, told reporters in the German capital that Tymoshenko, 51, was under constant surveillance in a hospital room kept in darkness most of the day.

A military court handed stiff prison terms to 19 Ukrainians, three nationals from Belarus and two Russians accused of serving as mercenaries for ousted leader Moammar Gadhafi in Libya's conflict last year.

One of the Russians, judged to have been the coordinator, was condemned to life imprisonment while the others were sentenced to 10 years' hard labor.

The speaker of Ukraine's parliament on Friday called for the chamber to be disbanded and early elections held after deputies got into an ugly brawl over a proposed new language law.

Members of President Viktor Yanukovych's party came to blows on Thursday with lawmakers who opposed legislation expanding the use of the Russian language in courts and hospitals in the country's eastern regions that have close ties to Moscow.

Two commuter trains collided head-on in Warsaw Wednesday, injuring two people, on a stretch of railway near Poland's new national stadium where the Euro 2012 football championships kick off in June.

The crash caused major train delays, Polish State Railways spokesman Miroslaw Siemieniec said, according to PAP news agency. He said it was not yet known why both trains were travelling in opposite directions on the same track.

Slammed by UEFA chief Michel Platini for allowing Euro 2012 hotel prices to sky-rocket, embattled co-host Ukraine has tried to make good on a pledge to try to ease the burden on fans' pockets.

"We've seen that there is now more on offer, so prices have gone down," UEFA spokesman Thomas Giordano told Agence France Presse. "It's clear that there is still overpriced accommodation out there but nobody's going to book it," he added.