The acting president of Chechnya was the victim of an attempt to poison him and in a serious condition in hospital, a week ahead of elections in the turbulent region.
Mr Anatoly Popov was appointed prime minister of Chechnya earlier this year to serve under the head of the region's pro-Moscow local administration, Mr Akhmad Kadyrov.
Mr Popov has served as acting president during the campaign for the October 5th presidential poll, in which Mr Kadyrov is heavy favourite after his main rivals in the contest either withdrew or were disqualified.
"The diagnosis is poisoning by a substance of unknown origin," the Chechen government's press service said of Mr Popov, who is not running in the election.
"He is currently in one of Chechnya's hospitals and will soon be taken to Moscow. He is in serious condition."
The Chechnya election is a key plank in President Vladimir Putin's plan to end a decade of separatist violence.
Armed rebels, who subject tens of thousands of Russian forces to daily attacks, reject the poll as meaningless and have pledged to disrupt it.