With at least 21 civilians killed, dozens of police dead or wounded and an overnight truce in shatters, events in Ukraine moved quickly on Thursday.
European Union officials told news agencies late Thursday that the 28-country bloc's foreign ministers had agreed to impose visa bans, asset freezes and restrict the export of anti-riot equipment to Ukraine.
Vice President Joe Biden and Ukrainian President Yanukovych spoke by phone on Thursday evening, but details of their conversation were not released.
German Chancellor Angela Merkel and President Barack Obama had earlier discussed possible steps toward ending the violence in Kiev, also during a phone call, Reuters reported.
The latest developments came after it emerged that Merkel had telephoned Ukrainian President Viktor Yanukovych on Thursday to urge him to accept an offer from the EU, Germany and other partners to support talks between the Kiev government and opposition after violence escalated once more on Thursday.
Later Thursday, a statement from the Kremlin announced that Russian President Vladimir Putin was sending an envoy to Ukraine at the request of President Viktor Yanukovich, to try to mediate talks between the government and opposition.
Yanukovich telephoned Putin and asked him "to send a Russian representative to Kiev," the Kremlin said in a statement.
"Vladimir Putin decided to send human rights ombudsman Vladimir Lukin on this mission," it said.