Ukraine could risk creating a civil war if they don't "get their house in order", the European Union's justice chief told CNBC.
Ukrainian President Viktor Yanukovich met opposition leaders Wednesday in an attempt to defuse street violence.
Protesters clashed with riot police in the Ukrainian capital on Sunday after tough anti-protest legislation was rushed through parliament last week.
At least ten people were injured in the early hours of Saturday morning in clashes between riot police and protesters outside a courthouse in Ukraine.
Arseniy Yatsenyuk, leader of the All Ukrainian Union Fatherland, says the majority of Ukrainians support integration in the European Union, as Russia would not help implement the necessary reforms.
Ukraine might have recently decided to strengthen its financial ties with Russia but the EU should not abandon the country, an opposition leader said.
Ukraine's president could secure loans from Russia on Tuesday when he meets Vladimir Putin at the Kremlin.
Ukraine has compiled a list which identifies members of Kiev's foreign business community as threats to the country.
The International Monetary Fund issued a scathing report on Ukraine's financial situation, the New York Times reports.
U.S. Senator John McCain met Ukrainian opposition leaders in Kiev and voiced support for protesters camped out for weeks in the capital.
Thousands massed on Sunday for a rally against President Viktor Yanukovich just days before he heads for a meeting at the Kremlin.
Ukrainian riot police moved in force early on Wednesday into part of the Kiev square where protesters are demonstrating against government decision.
Riot police encircled central Kiev on Monday night, raising fears the authorities were preparing a crackdown on anti-government protesters. The FT reports.
The Ukrainian security services have launched a criminal investigation into "activities aimed at overthrowing the government" as protests intensify.
Ukraine's opposition accused President Viktor Yanukovich of betraying national interests after talks with Russia, though both countries said nothing had been agreed.
Massive protests against Viktor Yanukovich hammered Ukraine's financial markets on Monday, increasing the risk of a currency crisis.
Steven Pifer, senior fellow at the Brookings Institute, says the Ukrainian president's options are getting "very narrow", as protests against his decision to call off a deal with the European Union continue.
A protest by about 300,000 Ukrainians angered by their government's decision to freeze integration with the West turned violent Sunday. NBC reports.
Ukraine's rejection of a EU trade deal, was met with dismay. However, economic analysts said a move towards Russia and away from Europe could benefit Ukraine over the coming months.