The Ukrainian government has allowed an opposition activist to fly abroad for treatment after his abduction, torture and then attempted arrest by police angered critics of President Viktor Yanukovich.
Dmytro Bulatov, 35, whose bloodied face and account of being "crucified" during a week in the hands of mysterious kidnappers has dominated opposition media since Friday, flew to Lithuania, an EU state, on Sunday.
Bulatov, who has said he was seized and held by captors who cut off his ear and drove nails through his hands, flew into Vilnius where he will receive medical treatment.
Intense negotiations with Western diplomats had led to a court lifting a charge of "mass disorder" against him, on which police had tried to arrest him at a Kiev clinic.
"Without the support of the European community, this would not have happened," Vitaly Klitschko, former world champion boxer and Ukrainian opposition leader, told Reuters news agency.
"International pressure gives us a chance to fight for freedom in Ukraine."
Yanukovich, 63, caught in a tug of war between Russia and the West and facing mass protests that have prompted fears of civil war, announced on Sunday he would return from four days of sick leave on Monday.
Political breathing space
Yanukovich announced on Thursday he was taking sick leave for a severe respiratory infection, though he continued to sign legislation, including the repeal of laws curbing rights to protest and a conditional amnesty for dozens arrested during demonstrations - neither of which satisfied his critics.
Some suggested his illness was an excuse for political breathing space after Arseny Yatsenyuk, parliamentary leader of the main Batkivshchyna opposition party, turned down an offer of taking over as prime minister a week ago.
With the opposition so far receiving only verbal pledges of international support, Yatsenyuk, a former economy minister, told a rally of more than 60,000 people in Kiev on Sunday that it was time for "real financial aid".
|Bulatov told he can leave Ukraine
He called on the authorities to free 116 prisoners, as well as the leader of his party and former prime minister, Yulia Tymoshenko, whose freedom has also been a demand of the EU since she was jailed in 2011.
For his part, Klitschko said there was also a need for an international role to avoid "misunderstandings" in negotiations between the opposition and Yanukovich that have proved inconclusive.
Klitschko told the Kiev rally that he and other opposition leaders discussed with Western officials in Munich, Germany, bringing in international mediators to smoothe talks with Yanukovich.
Meanwhile, Catherine Ashton, EU foreign policy chief, said she was working with the US on a "Ukrainian Plan" to help support the economy through a period of political transition.
Ashton told the Wall Street Journal newspaper that the US and EU were developing a package of aid and guarantees to shore up the economy while a broad-based interim government could approve political and economic reforms and prepare for presidential elections, currently due next year.
That could help Ukraine weather any withdrawal of support from Russia, which in November pledged $15bn of aid.
Ashton is due in Kiev on Tuesday for her latest talks. Victoria Nuland, US assistant secretary of state, will also visit Ukraine again in the next few days.
Yanukovich issued a statement on Sunday saying he was well after treatment and planned to be at work on Monday - raising expectations he is ready to make further moves on the crisis.
He is under scrutiny from the EU and the US, who want him to compromise, and from Russia, which is holding back much needed financing until he names a new government following last week's departure of his prime minister in a concession that failed to appease the protesters.
Yanukovich has been caught in a dilemma since a last-minute change of heart in November saw him reject a trade deal with the EU and turn instead for economic support to Ukraine's old master Russia, which had threatened trade sanctions if Ukraine allied with the EU.
Yanukovich retains the loyalty of a substantial section of the 45 million population, notably among Russian speakers in the east.
A weekend poll showed he would top a multi-candidate presidential election with about 20 percent of the vote.