Prosecutors have accused Ukraine’s jailed former prime minister Yulia Tymoshenko of organising the 1996 murder of a powerful lawmaker and warned that a guilty verdict could put her behind bars for life.

Prosecutor-General Viktor Pshonka said the fiery 52-year-old has been informed by prosecutors that she and another former prime minister detained in the United States are formal suspects in the murder of deputy Yevgen Shcherban.

“We have collected evidence from the pre-trial investigation indicating that Tymoshenko really did order this murder together with (former prime minister Pavlo) Lazarenko,” Pshonka told reporters. “Today, an investigative team from the prosecutor-general’s office visited Tymoshenko in order to hand her (her documents on) suspicion of having committed a crime.”

He said the charismatic but divisive opposition leader has been named as a suspect under an article of the criminal code that meant she could spend the rest of her life in jail.

Tymoshenko’s defence once again denied her involvement and called the charges political.

“This is not a legal case – it is a political one,” defence attorney Sergiy Vlasenko told AFP.

“When talking about this murder, one has to remember who stood to gain from it. Tymoshenko had absolutely nothing to gain from Shcherban’s murder,” the lawyer said.

Tymoshenko was controversially sentenced to a seven-year jail term in 2011 amid Western outrage at her treatment by the government of President Viktor Yanukovych – her recent bitter foe.

She is being treated for back pain in a hospital outside her prison in the eastern Ukrainian city of Kharkiv.

The start of her second trial on embezzlement and tax evasion has been delayed until February 12 because of her medical condition.

When the court announced the adjournment, a group of her supporters called out: “Shame on the torturers!”

On January 8, the politician announced that she was launching a disobedience campaign in protest at measures such as the installation of video cameras in her hospital quarters.

She has refused to return to her hospital bed and has been sleeping in a chair in the hospital corridor, her supporters say.

At an emotional press conference, her defence counsel Vlasenko said: “Yulia Tymoshenko’s health condition is sharply worsening.”

Visibly upset by his visit to the hospital to see her, Vlasenko said he had found her lying in the shower room in her quarters.

“When I entered, I thought she had died. For two minutes, she couldn’t recognise me. I had to call for the head doctor. I am not an expert, but in my opinion the situation is critical,” he said.

Both the 2004 pro-democracy “Orange Revolution” leader and her supporters claim that all the charges against her as well as the murder investigation are retribution by the Yanukovych government.

The murder case against Tymoshenko and Lazarenko – a close ally who was convicted and jailed for money laundering in the United States in 2006 – states that the two paid $2.8mn to a contract killer to eliminate Shcherban.

The influential politician and affluent businessman was gunned down in a gangland-style shooting at an airport in the Ukrainian city of Donetsk in November 1996.

He was slain by two men who pulled up to Shcherban in a car as soon as he stepped down from a passenger jet onto the tarmac. His wife and driver also died in the attack.

His murder became one of the most notorious in a turbulent decade for the former Soviet republic in which huge state enterprises were distributed for pennies on the dollar to rival business groups.

One of the clans came from Shcherban’s Donetsk region. Tymoshenko herself is a native of the city of Dnipropetrovsk and has been linked to rival groups from that region.

Ukraine’s prosecutor-general said the murder case will be combined with embezzlement and tax evasion charges due to be heard next month.

The decision suggests an eagerness by Ukrainian authorities to speed up the case against Tymoshenko after months of delays on account of her ill health.

Tymoshenko’s prosecution has jeopardised Ukraine’s relations with both Western Europe and the United States.

The European Union has made the release of Tymoshenko and her former government allies a precondition for the signature of a document establishing broader trade and political relations between the two sides.

The document’s signing is seen as mandatory for Ukraine’s potential future membership of the 27-nation alliance.