Jailed Ukrainian opposition leader Yulia Tymoshenko's trial for tax evasion was adjourned again today.

Her defence counsel warned that her declining health has slumped to a "critical" level.

The former prime minister, the main opponent of President Viktor Yanukovych, was sentenced to seven years in prison in October 2011 on abuse-of-office charges.

But hospital treatment for back trouble has meant a second trial for alleged tax evasion and embezzlement, which she and western governments denounce as politically motivated, has been repeatedly adjourned.

When the court announced another adjournment today until 12 February, a group of her supporters called out: "Shame on the torturers!"

On 8 January, the 52-year-old announced 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 a press conference, her defence counsel, Serhiy Vlasenko, said: "Yulia Tymoshenko's health condition is sharply worsening."

Visibly upset by his visit to the hospital to see her, Mr 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.

Ms Tymoshenko denies any wrongdoing and says she is being persecuted by Mr Yanukovych in revenge for her role in the 2004 "Orange Revolution" protests, which derailed his first bid for presidency.

She lost a run-off for the presidency against Mr Yanukovych in February 2010 and subsequently she was tried for abuse-of-office over a gas deal she brokered with Russia in 2009 when she was prime minister.

The new tax evasion and embezzlement charges date back to the 1990s when she ran a major gas trading company.

The European Union has supported Ms Tymoshenko, calling her case an example of selective justice, and shelved agreements on free trade and political association with Ukraine over the issue.