Italy's Foreign Ministry has urged Ukrainian authorities to investigate the death of reporter Andrea Rocchelli, who was killed in a mortar shell attack on Saturday in Slaviansk.

"We urge the Ukrainian authorities to track down the dynamics of the attack which killed Andrea Rocchelli", a statement on the ministry's website read.

Foreign Minister Federica Mogherini expressed her condolences to the family of the reporter and his Russian interpreter, who was also reported killed. She voiced her hopes that peace would be restored in Ukraine after the presidential elections.

Clashes between Ukrainian and pro-Russian forces intensified on Saturday around Slaviansk, in the Donetsk region. Polling stations around most of the self-proclaimed Donetsk People's Republic remained closed during Sunday's presidential elections.