All Serbian citizens who reported to the Serbian embassy in Kiev have left the unsafe zone and traveled to Serbia via Kiev, a statement added.

The Belgrade-based daily Blic previously quoted a Kiev NGO which claimed that among the pro-Russian fighters killed in Donetsk were Serbian citizens.

A Ukrainian website, podrobnosti.ua, first published these claims presented by Dmitry Tymchuk, coordinator of the "Information Resistance."

"According to our data, the mercenaries who were killed during the last three days in this part of Ukraine, in addition to citizens of Ukraine, have been identified as Serbs, Russian citizens from Ingushetia, Chechnya, Dagestan, and residents of Abkhazia," said Tymchuk.

According to the Beta news agency, "the respected Institute for War and Peace Reporting also carried this statement on its website."