The European Union says it is putting on hold work with Ukraine on a trade agreement, saying Ukraine government arguments have "no grounds in reality".
EU enlargement chief Stefan Fuel tweeted that he had told Ukraine's first deputy prime minister Serhiy Arbuzov last week that further discussion on the trade agreement was conditional on a "clear commitment" by Kiev to sign. However, Mr Fuel said he had not heard back from the Ukraine government.
Ukraine president Viktor Yanukovych previously rejected a deal with the EU, leading to weeks of demonstrations.
The trade deal was set to strengthen ties between Ukraine and the EU.
There is an urgent need for de-escalation in Ukraine as President Yanukovich tries to calm a country bitterly divided over years of history.
Ukraine's political and economic landscape is stuck between old Soviet masters in Russia and the democratising ideals offered by the EU.