Russian Foreign Minister Sergey Lavrov says the killing of opposition leader Boris Nemtsov was a "heinous crime which will be fully investigated."

Nemtsov was shot dead Friday night near the Kremlin. Western officials have called on Moscow to conduct a prompt and transparent probe of the killing.

Lavrov told the U.N. Human Rights Council in Geneva on Monday that Russian President Vladimir Putin had "immediately handed down all instructions and is ensuring special control over this investigation."

At the same time he rebuffed outside interference in the probe, saying that any "attempt to use the heinous killing of Boris Nemtsov for political purposes is despicable."