KIEV (REUTERS) - Western powers threatened sanctions on Wednesday over the death of 26 people in the worst violence since Ukraine's independence from the Soviet Union, pressuring President Viktor Yanukovich to compromise with his pro-European opponents.
Mr Yanukovich, backed by Russia, denounced the overnight bloodshed in central Kiev as an attempted coup, and his security service said it had launched a nationwide "anti-terrorist operation" after arms and ammunition dumps were looted.
In the western bastion of Ukrainian nationalism, a regional assembly declared self-rule and crowds seized public buildings.
US President Barack Obama said he condemned the violence in the strongest possible terms and warned of consequences if it continued, while European Union leaders said they were preparing targeted sanctions against those responsible for the"unjustified use of excessive force by the Ukrainian authorities".
EU officials said Mr Yanukovich himself would not be on the list to keep channels of dialogue open. The foreign ministers of Germany, France and Poland will visit him on Thursday, hours before an emergency EU meeting to decide on the sanctions.
The United States, going head to head with Russia in a dispute heavy with echoes of the Cold War, urged Mr Yanukovich to pull back riot police, call a truce and talk to the opposition.
Pentagon spokesman Colonel Steve Warren urged the Ukrainian armed forces to stay out of the conflict, warning that"participation would have consequences in our defense relationship".
Earlier on Wednesday, Ukraine's defence ministry said the armed forces might take part in a countrywide anti-terrorist operation organised by the state security service.
A presidential decree later appointed a new head of the armed forces general staff, naming navy head Admiral Yury Ilyin in place of Colonel-General Volodymyr Zamana. The decree gave no explanation for the change in personnel, nor for the timing.
Protesters have been occupying central Kiev for almost three months since Yanukovich spurned a far-reaching trade deal with the EU and accepted a US$15-billion (S$19 billion) Russian bailout instead.
Russian President Vladimir Putin and Mr Yanukovich spoke by telephone during the night and both denounced the events as an coup attempt, a Kremlin spokesman said.
Russian Foreign Minister Sergei Lavrov blamed the West for encouraging opposition radicals "to act outside of the law".
Moscow announced on Monday it would resume stalled aid to Kiev, pledging US $2 billion hours before the crackdown began. The money has not yet arrived and a Ukrainian government source said it had been delayed till Friday "for technical reasons".
Ukraine's hryvnia currency, flirting with its lowest levels since the global crash five years ago, weakened to more than 9 to the dollar for the second time this month.
The Health Ministry said 26 people were killed in fighting in the capital, of whom 10 were police officers. A ministry official said 263 protesters were being treated for injuries and 342 police officers, mainly with gunshot wounds.
European Council President Herman Van Rompuy said the 28-nation EU, at an emergency meeting on Thursday, would impose asset freezes and visa bans on those blamed for the bloodshed.
US Secretary of State John Kerry, on a visit to Paris, said Washington was ready to impose similar sanctions.
The European Investment Bank, the EU's soft-loan arm, said it had frozen its activities in Ukraine due to the violence.
German Chancellor Angela Merkel said targeted sanctions against Ukraine's leaders would show the EU was serious in pressing for a political solution. She made clear they were talking to all sides in the crisis, including Russia.
Merkel said she and Putin had spoken by phone and agreed to do everything to avoid an escalation of violence.
Ukraine has been rocked periodically by political turmoil since independence from the Soviet Union more than 22 years ago, but it has never experienced violence on this scale.