(Reuters) - Lithuanian film director Mantas Kvedaravicius was killed on Saturday in Ukraine's Mariupol, where he had long documented the besieged port city, according to colleagues and a media report.

"Our friend Artdocfest participant, Lithuanian documentary writer Mantas Kvedaravicius, was murdered today in Mariupol, with a camera in his hands, in this shitty war of evil, against the whole world," the Russian film director Vitaly Mansky, the founder of a festival of documentary movies Artdocfest, said on Facebook.

Reuters could not immediately verify the report.

Kvedaravicius was known, among other works, for his conflict-zone documentary "Mariupolis", which premiered at the 2016 Berlin International Film Festival.

Filmed in Mariupol, it is the portrait of a Ukrainian city under siege with a strong will to live. The strategic port is in the breakaway region of Donetsk, neighbouring Russia, where pro-Russian fighters have been fighting Ukrainian forces since 2014.

Now Mariupol, encircled since soon after Russia's Feb. 24 invasion, is Moscow's main target in Ukraine's Donbas, the southeastern region including the Donetsk and Luhansk breakaway areas. Tens of thousands are trapped in the city with scant access to food and water.

"Everyday life develops a poetry of its own, which occasionally can seem absurd," said the Berlin International Film Festival's synopsis of "Mariupolis".

Kvedaravicius was born in 1976, studied at Vilnius University and got a degree in social anthropology from the University of Cambridge, according to the Lithuanian public broadcaster LRT.

The broadcaster, which also reported Kvedaravicius's death, said it has not been officially confirmed yet.

"RIP dearest talented Mantas. A terrible loss for Lithuanian cinema community and all the world. Our hearts are broken," Giedre Zickyte, a Lithuanian documentary film director and producer, wrote in her Facebook account.