Ukraine's former president Viktor Yushchenko gave dramatic testimony Wednesday against his one-time premier and fellow Orange Revolution leader Yulia Tymoshenko in her controversial abuse of power trial.
Yushchenko was met by cries of "Shame!" from Tymoshenko's supporters as he entered the court room to give evidence that could help put his former friend behind bars for up to a decade.
The former prime minister is accused of overstepping her authority when signing a 2009 deal with Russia that raised the price Ukraine had to pay for its gas.
The trial has seen Ukraine come under intense criticism from the EU nations just as the two sides enter talks on a closer commercial union that could see Kiev slip further away from Moscow's influence.
Yushchenko's successor and Tymoshenko's main rival Viktor Yanukovych has said that as president he has no right to intervene in the case and brushed aside suggestions that it was a part of a broader political vendetta.
Tymoshenko could avoid jail but still be prevented from re-joining politics should she be found guilty and then pardoned by Yanukovych -- an option feared by some of her supporters.
Yushchenko was a close ally of Tymoshenko and the two jointly spearheaded pro-democracy rallies in 2004 that prevented Yanukovych from seizing power in fraudulent elections.
But the two had a profound falling out while serving together in government and Yushchenko has been called on to testify as a witness for the prosecution.
He arrived accompanied by a bodyguard and soon began recalling in a calm voice the details of a conflict that led to a temporary halt in gas supplies to Europe and led to an accusation of energy being used as a weapon by the Kremlin.
Yushchenko said he did not have the authority to prevent his prime minister from signing the inter-government agreement with Russia even though it looked like a bad deal.
He said Tymoshenko had refused to accept a more reasonable price set by Russia and was later forced to accept revised Russian terms that dramatically raised the price of gas.
"There was a complete breakdown in the negotiations," Yushchenko said.
He added that Tymoshenko had at one stage realised her mistake and attempted to fly to Moscow to sign the initial terms of the Russian deal.
"This was never realised because the Russian side" had by that stage refused to deal with Tymoshenko, the former president said.
Tymoshenko has been shuttled to court hearings from her prison cell since being placed under arrest for contempt of court on August 5.
Kiev courts have rejected seven motions by Tymoshenko's friends and relatives to release her on bail -- the last one made Tuesday by her daughter Yevgenia Carr.
Tymoshenko has found broad support for her case in the West and this week penned an article from prison in which she thanked foreign powers for their reaction to the "persecution of the opposition" in Ukraine.
She said it was "Yanukovych and his clan" who stood on the brink of international isolation and not Ukraine itself.