Yulia Tymoshenko, the former Ukrainian prime minister serving a prison sentence for abuse of office, has reportedly gone on hunger strike.
Her fast began on Friday, lawyer Serhiy Vlasenko told Interfax news agency, speaking outside the walls of her prison in the eastern city of Kharkiv.
She is serving seven years in prison for abuse of office, a conviction which caused dismay in the West.
Reports say she has been suffering back pain for months.
Mr Vlasenko was quoted by Interfax as saying Tymoshenko was protesting against "what is happening in the country and what is happening to her in prison".
She had, he said, suffered bruising to her arms and stomach as a result of being moved from the prison to a hospital on Friday.
'Confined to bed'
The lawyer denied his client had refused to allow doctors to examine her but he added that she had been put in hospital against her will.
She is currently unable to get out of her bed, he said.
There was no immediate confirmation of Tymoshenko's hunger strike from the prison authorities.
The day before she was taken to hospital, Tymoshenko had been due to attend a new trial for tax evasion. However, she refused to attend, citing problems with her health.
She denies wrongdoing as head of a gas trading company in the 1990s.
Her conviction last year for abuse of office over a 2009 gas deal with Russia was condemned in Western states as politically motivated.
She has accused Ukrainian President Viktor Yanukovych, a former rival, of seeking revenge.
The issue has overshadowed talks on co-operation between Ukraine and the EU.
Tymoshenko is serving her sentence in Kachanivska prison, Kharkiv, having been moved there from a Kiev detention centre in December.