Sergei Loznitsa/ REUTERS

Ukrainian director Sergei Loznitsa has won The Best Director prize in the Cannes Film Festival's Un Certain Regard competition for his film "Donbass.".

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"The Best Director prize on the other hand, went to an auteur with established Cannes credentials: Ukraine's Sergei Loznitsa, who opened the Un Certain Regard section with his fevered, surreal war study 'Donbass'," Variety wrote.

A sometime docmaker who continues to experiment radically with form in his narrative work, Loznitsa has been in Competition at Cannes three times, most recently with last year's harrowing anti-administration protest "A Gentle Creature." That he was dropped to the lower-profile Un Certain Regard strand with his latest, a study of conflict between Ukrainian nationalists and Russia's "Donetsk People's Republic", suggests Cannes selectors may have deemed it more of a niche item than his previous work, the publication said.

Variety's Jay Weissberg agreed, forecasting that the film would "struggle to find audiences beyond Loznitsa fans," but was nonetheless impressed by "[a scream] against a society that's lost its humanity and can't be bothered to care." Loznitsa, also not present at the ceremony, sent a statement both thanking the festival and protesting Russia's imprisonment of Ukrainian filmmaker Oleh Sentsov.