KIEV (Reuters) - Ukraine's authorities kept up pressure on jailed former prime minister Yulia Tymoshenko on Wednesday, saying she was being investigated as a material witness in an unsolved 16-year-old murder case.
Tymoshenko, who is serving a seven-year jail sentence over abuse-of-office charges, has already said allegations that she was involved in the 1996 murder of a powerful businessman and politician in eastern Ukraine are "absurd".
The jailing last October of Tymoshenko, the main opponent of President Viktor Yanukovich, has soured Ukraine's ties with the European Union and the United States. They say the case smacks of "selective" justice.
But despite Western pressure for her release on the eve of the Euro 2012 soccer championship, which Ukraine is co-hosting, prosecutors have additionally accused her of tax evasion and are looking at her possible involvement in the contract killing of Yevhen Shcherban.
"At the present time, Tymoshenko has the status of a (material) witness in any investigation that is going on ... An investigation is under way to unmask those who ordered this serious crime," general prosecutor Viktor Pshonka said.
Shcherban died in a hail of bullets as he emerged from a plane in the eastern city of Donetsk. The attackers, disguised as airport mechanics, also killed his wife and several bystanders.
His killing followed several other murders in Donetsk, including a football stadium bombing that killed the owner of Shakhtar Donetsk club, and led to a realignment of political and business alliances in the key steel- and coal-producing region.
At the time, both Tymoshenko and Yanukovich were big players in a turbulent region which seethed with intrigue and where fortunes were made and lost in murky dealings ranging from sales of state assets to protection rackets, extortion and theft.
Pshonka, speaking at a news conference on Wednesday, said investigators were trawling through evidence in the case, including new testimony from Shcherban's son.
Shcherban's son, Ruslan Shcherban, was 19 at the time and survived the attack by hiding under a car. But he has said recently that he has evidence implicating Tymoshenko.
"Linking me to the Shcherban case is absurd," Tymoshenko said in the statement last month issued by her party, Batkivshchyna. "I believe that people well understand how poorly this case holds together, who benefits from it and how absurd it is," she said.
Tymoshenko was one of the leaders of the 2004 Orange Revolution which doomed Yanukovich's first bid for the presidency. She went on to serve twice as prime minister.
But she lost the 2010 presidential election to Yanukovich and after his rise to power Tymoshenko and a number of her allies in opposition faced corruption-related charges in what she has described as a campaign of repression.
Writing By Richard Balmforth; Editing by Andrew Heavens