Britain has warned there must be an "international response" to the continuing violence in the Ukraine as European Union foreign ministers gathered to discuss sanctions against the government of president Viktor Yanukovych.
Arriving in Brussels, Foreign Secretary William Hague said there had to be an "immediate and far-reaching change" in attitude of the authorities in Kiev following the latest clashes between police and anti-government demonstrators which left more than 20 dead.
Earlier the Ukranian ambassador to London, Volodymyr Khandogiy, was summoned to the Foreign Office for the second time in as many days to be told that the action to crush the protests was "unacceptable".
Mr Hague said it was now up to the EU to put pressure on the the Ukrainian authorities to bring the bloodshed to an end.
"The United Kingdom condemns these actions in the strongest terms. By permitting such action to take place, the Ukrainian government is putting itself at odds with reasonable opinion all across the world," he said.
"It is not right to describe protesters as terrorists. A great many of them are simply seeking a better future for their country.
"I think the European Union has to act in a way that helps to stop the violence. There has to be an international response to what has happened over the last few days.
"It is time on all sides for people to turn away from violence but the Ukrainian government bears a particular responsibility to take the lead in making sure that happens."
The emergency session of EU foreign ministers comes after US president Barack Obama issued a warning yesterday that "there will be consequences" for Ukraine if the violence continues.
Possible sanctions could include asset freezes and travel bans against Ukrainian figures considered to be responsible for the crackdown against the demonstrators.
The clashes this week have been the most deadly since protests kicked off three months ago after Mr Yanukovych shelved an association agreement with the European Union in favour of closer ties with Russia. Moscow then announced a multibillion-pound bailout for Ukraine, whose economy is in tatters.
Europe Minister David Lidington, who summoned Mr Khandogiy to the Foreign Office, said that he had challenged the ambassador over reports that Ukrainian authorities were behind the latest killings.
"His reaction is that he was not able to give me a definitive view about that," he said.
"I said that these reports were particularly shocking, because if those reports are substantiated then that would suggest that people who were trained in marksmanship were involved, and that does point to people who have been trained officially in some way.
"But I think the key thing there is that, in light of what has happened, there should be a full and independent and thorough investigation of those killings - the people responsible for those shootings need to be held to account, wherever they come from."