The United States government says it is preparing to impose further targeted sanctions on Russia over its actions in Ukraine and that European leaders have agreed to coordinate on steps to make Moscow pay.
The crisis escalated when armed pro-Russian separatists in the eastern city of Slaviansk seized a bus carrying international mediators. A separatist leader said the mediators were believed to have a Kiev “spy” amongst them.
The White House said on Friday that the U.S. President, Barack Obama and European allies all felt that Russia had escalated tension in eastern Ukraine, where pro-Moscow separatists have refused to leave official buildings they have occupied.
But it gave no details of what the sanctions might be, or when it planned to enact them.
Ukraine sent troops to try to dislodge the separatists from Slaviansk on Thursday, killing up to five rebels in what it said was a response to the kidnapping and torture of a politician found dead on Saturday.
Special forces launched a second phase of their operation on Friday by mounting a full blockade of Slaviansk, the rebels’ military stronghold, an official on the presidential staff said.
One of its military helicopters was hit by rocket fire and exploded while on the ground at an airport near the city, the Defence Ministry said.
Pro-Western leaders in Kiev, who took power in February after Moscow-ally President Viktor Yanukovich fled following mass protests against him, say the rebels are being directed by Moscow. Russian troops seized Crimea soon after Yanukovich fled.
The standoff has led to heavy capital flight from Russia, prompting credit rating agency Standard & Poor’s to cut the country’s ratings on Friday. That forced Russia’s central bank to raise its key interest rate to reverse a drop in the ruble.
Russia’s foreign minister, Sergei Lavrov, accused authorities in Kiev of waging “war on their own people”.
“This is a bloody crime, and those who pushed the army to do that will pay, I am sure, and will face justice,” Lavrov said.
The Kremlin says it has the right to defend Russian speakers anywhere if they are under threat and has deployed extra troops on the border with Ukraine, which NATO says number up to 40,000.
They began military exercises on Thursday and Ukraine said they had approached to within 1 kilometer (1,100 yards) of its border and that it would treat any incursion as an invasion.
Ukraine’s acting president accused Moscow of supporting “terrorism at the state level” against his country for backing the rebels, who it blames for the politician’s murder.
Interior minister Arsen Avakov insisted that every care was being taken to avoid non-combatant casualties, after Moscow warned it may act if Kiev used the army against civilians.