An uneasy calm appears to have returned to the eastern Ukrainian city of Donetsk, one day after dozens of pro-Russian separatist fighters were reported killed in fighting with government forces.
Intense gunfire was reported earlier on May 28 around the Ukrainian Security Service (SBU) building occupied by the separatists, and jet fighters were heard flying over the city.
There were, however, no immediate details on fighting, and the gunfire later stopped.
In a statement, the mayor denied that the separatists had seized more public buildings in the city.
In an interview with Germany's "Bild" daily, the winner of Ukraine's presidential election, Petro Poroshenko, said that "the antiterrorist operation has finally begun in earnest."
"A real war is being waged against our country," he added. "We will end this terror."
Russian Foreign Minister Sergei Lavrov said that the Ukrainian people were "in essence being pushed into the abyss of fratricidal war."
An aide to Russian President Vladimir Putin, Yury Ushakov, said that what he described as the Ukrainian government's "provocative" military actions in eastern Ukraine were pushing the crisis further into deadlock.
The pro-Russian separatists said dozens of separatist fighters were killed during nearly 24 hours of fighting for control of the city's international airport that began on May 26. Some rebel leaders said up to 100 fighters had been killed.
Ukrainian officials said there were Russians and Chechens among the dead and wounded.
On May 28, Chechen leader Ramzan Kadyrov denied that he had sent soldiers to help the pro-Russian separatists, but did not rule out that some Chechen volunteers could have gone there on their own.
A Polish priest, who had been missing since May 27 and was believed to have been held by the separatists, was freed. No further details on his release were immediately available.
There was also no news on the whereabouts of a team of OSCE monitors who have been missing since May 26 while on patrol east of Donetsk.
With reporting by UNIAN, Reuters, and ITAR-TASS