Imprisoned Ukrainian opposition leader Yulia Tymoshenko has accused President Viktor Yanukovych of seeking to undermine the country's EU aspirations.
She said the arrest of her lawyer, Serhiy Vlasenko, was "the last stab" in the heart of hopes of signing a long-awaited agreement with Brussels.
Mr Vlasenko, who was detained on Monday on suspicion of beating his former wife, has been freed on bail.
He has dismissed the charges against him as a "total lie".
Tymoshenko described the charges against her lawyer as "absurd".
The former prime minister has been serving a seven-year jail term since being convicted of abuse of power in 2011 over a controversial gas deal with Russia - a conviction she insists was politically motivated.
Brussels is calling for her release as a condition for signing the wide-ranging association and free trade agreement, which would challenge Ukraine's traditionally close ties with Russia.
The plan is to sign the deal in Lithuania at the end of this month but the uncertainty about Tymoshenko has fuelled doubt about whether it will go ahead.
Ukraine's parliament is to vote on Wednesday on legislation which would allow Tymoshenko to leave Ukraine for medical treatment abroad. EU monitors have set Wednesday as the deadline for resolving the Tymoshenko issue.
In a letter published by Ukrainian media, Tymoshenko said: "Yanukovych wants to convince European leaders that their efforts to protect Ukraine against dictatorship are futile, and they have to give up and retreat."
She accused Mr Yanukovych, who defeated her at the 2010 presidential election, of undermining political opposition and blocking "European laws" in Ukraine.
"To feel absolutely confident, Yanukovych decided to act in a no-lose way and to definitely kill the agreement by his aggression against Serhiy Vlasenko," Tymoshenko said.
Mr Vlasenko was freed on bail of 22,940 hryvnia (£1,720; $2,760; 2,060 euros) on condition he did not leave the Ukrainian capital Kiev, other than to visit his client in Kharkiv.
He said the accusations were aimed at depriving Tymoshenko of competent defence.
His former wife, Natalia Okunskaya, has accused him of striking her in front of witnesses a few years after they split up in 2008.
"He [Mr Vlasenko] is suspected of carrying out physical harm to his former wife and also of carrying out acts of violence in his relations with her," Ukrainian prosecutors said in a statement.