Tymoshenko is serving a seven-year prison sentence after being found guilty of abuse of office for attempting to broker a gas deal with Russia in 2009.
The former premier was taken to a clinic for an undisclosed medical condition. Her representatives said she was brought there against her will late at night in the best traditions of totalitarianism.
Local prosecutor Hennadiy Tyurin said that Tymoshenko refused to go to the clinic voluntarily.
She got her things together, got dressed and then laid down in bed and said: 'I am not going anywhere.' According to the law and the criminal administrative code, the prison service has the right to use physical force. They took her in their arms, carried her to the vehicle and took her to hospital, said Tyurin to Interfax, a Russian news agency, according to the AFP.
She was moved back to her prison within a day after refusing treatment at the clinic.
It doesn't make any sense, it's just insane. Why first force her into the hospital and then kick her out the next day? Serhiy Vlasenko, Tymoshenko 's lawyer, told the Associated Press. He called the situation absurd.
He said she suffered from bruising on her arms and stomach from being shuttled back and forth between the prison and the hospital.
Tymoshenko's political party, the All-Ukrainian Union Fatherland, released a statement saying that the shuffling back and forth was done by officials to give her bad publicity.
First Tymoshenko was secretly taken to a hospital at night... (late on Friday) and then on Sunday she was suddenly returned to jail, her party said in a statement, according to Reuters.
It is absolutely clear that nobody had planned to treat the former prime minister and all of this was done only for negative publicity - to tell the whole country again that Tymoshenko refuses to get treated at the Kharkiv hospital.
Vlasenko said Tymoshenko has been on a hunger strike since Friday to protest against what is happening in the country and what is happening to her in prison, reported the BBC.
German doctors say Tymoshenko needs urgent specialized care for her illness. Her office says doctors claim her treatment could not have been provided by the clinic. However, Ukrainian health officials say her doctors approved of the clinic.
Tymoshenko suffers from a herniated disc that causes her intense pain. The government has refused to give her medical care for months and negotiations for treatment are still ongoing, reported the Associated Press.
Dr. Karl Max Einhaeupl said he examined Tymoshenko and says she needs urgent treatment.
I can tell you with full confidence: She is ill, Einhaeupl told Russia's state-owned Rossiyskaya Gazeta newspaper, according to the Guardian. She practically cannot move and is reduced to lying down most of the time.
Tymoshenko was the head of the All-Ukrainian Union Fatherland party, the top opposition group in the country. She ordered Naftogaz, the national oil and gas company, to sign a gas deal with Russia in January 2009, which exceeded her powers as prime minister. She was found guilty of abuse of office in October 2011, sentenced to prison, and ordered to pay $188 million fine.
Tymoshenko became prime minister of Ukraine in 2005, a position she held for less than a year. She was elected again in December 2007, and remained in office until March 2010. Prior to that, she co-led the Orange Revolution, a massive protest sparked by the 2004 presidential election.
She is standing trial on unrelated charges of evading taxes while heading an energy company in the 1990s, The Guardian reported. She claims her innocence and says President Viktor Yanukovych has conspired to keep her out of parliamentary elections in the fall.
If convicted she would have to serve an additional five years in prison, bringing her prison sentence to 12 years.