Russian President Vladimir Putin on Wednesday described the killing of Opposition politician Boris Nemtsov as a tragedy that had brought disgrace on Russia, and warned against a rise in “extremist crime”. “We must pay the greatest attention to crimes that prompt a major reaction, including those that are politically charged,” he told Interior Ministry officials at a televised meeting. “We must rid Russia of disgrace and tragedies like the one we just saw... The audacious murder of Boris Nemtsov right in the centre of the capital,” a grim-faced Putin said.