EU halts work on Ukraine trade deal
The protesters have been holding mass rallies in Kiev
every weekend since President Yanukovych pulled out of the EU agreement
The European Union has suspended work
on an association agreement with Ukraine after failing to get a "clear
commitment" from President Viktor Yanukovych to sign it.
Mr Yanukovych - apparently under pressure from Russia - backed out of signing the trade deal in November.
But Ukraine and the EU had said they would continue negotiating.
Some 200,000 people turned out in Kiev on Sunday to protest against Mr Yanukovych's failure to sign.
The announcement by Stefan Fuele that the EU was suspending talks with
Ukraine over a wide-ranging political and free trade agreement will undoubtedly
stoke the already high tensions in Kiev.
President Viktor Yanukovych has tried to mollify the crowds camping out in the capital's central Independence Square by assuring them that his government was serious about signing the treaty with the EU - just not right now.
But EU officials, it seems, have called Mr Yanukovych's bluff, saying they will recommence talks when the Ukrainians show sufficient commitment.
This means that the government has no way of satisfying one of the opposition's key demands - that the deal be signed immediately.
At the moment, tens of thousands of pro-Yanukovych supporters from eastern Ukraine are in Kiev; some are attending the second day of pro-government demonstrations, but many are simply milling about the capital. At the moment, all is calm. But the potential for clashes is ever present.
President Viktor Yanukovych has tried to mollify the crowds camping out in the capital's central Independence Square by assuring them that his government was serious about signing the treaty with the EU - just not right now.
But EU officials, it seems, have called Mr Yanukovych's bluff, saying they will recommence talks when the Ukrainians show sufficient commitment.
This means that the government has no way of satisfying one of the opposition's key demands - that the deal be signed immediately.
At the moment, tens of thousands of pro-Yanukovych supporters from eastern Ukraine are in Kiev; some are attending the second day of pro-government demonstrations, but many are simply milling about the capital. At the moment, all is calm. But the potential for clashes is ever present.
News agency estimates of the size of the crowd at
Independence Square ranged from 150,000 to 300,000.
This is the latest in a series of demonstrations over the past few weeks by the opposition who see Ukraine's future as part of the EU rather than aligned with Russia.
Sunday's protests are taking place near a much smaller pro-government rally, raising fears of possible clashes between the two groups, the BBC's David Stern reports from Kiev.
The series of protests, the largest since Ukraine's 2004 Orange Revolution, is designed to push Mr Yanukovych to dismiss his government and call fresh elections, opposition leaders say.
Makeshift barriers around the perimeter of the main protest encampment on Independence Square have been strengthened following an attempt by special police to dismantle them earlier this week.
Opposition leaders have urged protesters to remain vigilant, fearing "provocateurs" could trigger clashes between rival demonstrators.
'Work on hold'
The EU's frustration at the Ukrainian president's position on reaching a deal with the bloc was evident in a tweet from EU Enlargement Commissioner Stefan Fuele announcing the suspension of talks.
Police are on guard to prevent any new attempt to
block administrative buildings in central Kiev 
US Senator John McCain visited the protesters before
addressing the crowd. 
Pro-EU protesters have been painting themselves in
the colours of the Ukrainian flag. 
The protesters have continued to reinforce their
barricades in Ukraine's most famous public space. "Work on hold," he tweeted, adding that he had told Deputy PM Serhiy Arbuzov that Ukraine needed to show a "clear commitment to sign".
Mr Yanukovych has said he fears the association and trade agreement will put at risk many enterprises dependent on trade with Russia.
The president - who says he eventually aims to sign the deal - has also admitted being under heavy pressure from Moscow, which wants Kiev to join a Russian-led customs union instead.
He has said the EU would need to provide at least 20bn euros (£17bn; $27bn) a year to upgrade Ukraine's economy.
Moscow has already put economic pressure on Ukraine, with customs delays and a ban on Ukrainian chocolates, and there are concerns it could escalate such measures if Kiev drew closer to Brussels.
'Slaves of Europe'
A leading voice on United States foreign policy, Republican Senator John McCain, is in Kiev where he addressed the pro-EU protesters.
"Ukraine will make Europe better and Europe will make Ukraine better," he told them.
"We are here to support your just cause, the sovereign right of Ukraine to determine its own destiny freely and independently. And the destiny you seek lies in Europe," he said.
One unnamed protester in the crowd told the Associated Press news agency: "I have come here to defend my rights.
"My little nine-month-old child is waiting for me at home, and I don't want the government to steal his future. And of course, we want to join the EU."
President Yanukovych, who was elected in 2010, retains strong support outside Kiev, in the south and east of Ukraine.
At Sunday's pro-government demonstration in a Kiev park, demonstrator Maria Nikolayeva, 18, told Reuters news agency: "We are here to support the president and order. Yanukovych is our best prospect at the moment."
Another demonstrator, 43-year-old Sergei Antonovich, told AP why he rejected the association agreement.
"We'll become the slaves of Europe if we go into it," he said. "Look at history - only union with Russia can save Ukraine from catastrophe."
The pro-Yanukovych rally attracted fewer than 5,000 people.
