In the wake of an armed incident in Sloviansk, a town in Ukraine's Donetsk region, Kyiv urged Russia to assist implementation of the Geneva accords.

Russia should remember the obligations, assumed under the Geneva agreements, and "exert all necessary influence" on the pro-federalization forces in order "to get the illegally occupied premises vacated, roads unblocked, weapons surrendered and bloodshed prevented," the Ukrainian Foreign Ministry said in a commentary.

It also said that Ukrainian law enforcement services have launched an urgent probe into an incident in Sloviansk last night, which left several people killed and wounded.

Reports said earlier that three to five people were killed in a skirmish at a check-point in Sloviansk early on Sunday.

The Ukrainian Interior Ministry pledged to probe each media report about the use of fire arms and about casualties, after law and order are restored in Sloviansk.

The Russian Foreign Ministry earlier released a statement expressing indignation over the armed incident near Sloviansk early on April 20. "The Russian side condemns the militants' provocation, which indicates that the Kyiv authorities do not want to subdue and disarm the nationalists and extremists," the Russian Foreign Ministry said.

"The fact that this tragedy occurred after an agreement was signed in Geneva on April 17 following four-party talks between representatives of Russia, the United States, the European Union and Ukraine arouses surprise. The agreement carries a call to refrain from violence, intimidation and provocations. The Russian side insists on the rigorous implementation of the commitment to de-escalate the situation in southeastern Ukraine, assumed by the Ukrainian side," Moscow said.