New Delhi, June 18 -- Polish Prime Minister Donald Tusk Wednesday said the killing of a Russian artist who was critical of President Vladimir Putin has the hallmarks of a political assassination.

Robert Kuzovkov, known by the pseudonym Semyon Skrepetsky, was shot and killed at close range near his home in the eastern Polish city of Biala Podlaska on Monday, prosecutors said Tuesday.

"Everything points to this being a political murder," Tusk said at a news briefing in Warsaw. "But we must wait for evidence or more concrete indications. Because if that was the case - if it was ordered by Russia - then it is an extremely serious matter internationally. It would constitute state terrorism."

Polish investigators initially detained two Belar...