About 200,000 pro-European protesters massed Sunday in the Ukrainian capital against President Viktor Yanukovych's outreach to Russia, as the European Union indicated it is suspending association talks with Kyiv.
Minutes before the rally, EU enlargement chief Stefan Fuele said on Twitter the 28-nation bloc was halting talks until it received a firmer commitment from Mr. Yanukovych that Ukraine was serious about the deal.
He said the government's arguments to improve terms had "no grounds in reality."
Mr. Yanukovych is due Tuesday in Moscow for talks with Russian President Vladimir Putin that protesters occupying central Kyiv's iconic Independence Square fear could result in an even firmer alliance between the two neighbors.
Demonstrators were reassured of continued U.S. backing by visiting Senators John McCain and Chris Murphy, who threatened sanctions if authorities use more violence to disperse protests.
McCain and Murphy are the latest in a string of Western dignitaries to tour the huge makeshift protest encampment since demonstrations erupted last month over a presidential decision to back away from the key trade deal with the European Union.
Kyiv says it will instead focus on repairing and strengthening economic ties with Russia.
A much smaller rally of about 15,000 government supporters was also held Sunday about a kilometer away.
On Saturday, President Yanukovych, in a bid to ease tensions in the capital, suspended key government officials for their suspected roles in a violent November 30 police crackdown on demonstrators.
A poll by Ukraine's non-governmental Research & Branding group released earlier this month shows 46 percent of Ukrainians favoring the EU trade pact. Thirty-six percent were shown favoring a rival trade bloc of former Soviet republics and satellite countries that is being pushed by Moscow.