Updated

A U.S.-based Muslim cleric on Thursday condemned the killing of Russia's envoy to Turkey and rejected accusations that his movement was behind the attack.

Ambassador Andrei Karlov was shot dead by an off-duty policeman in front of stunned onlookers at a photo exhibition in Ankara earlier this week. Turkish President Recep Tayyip Erdogan has implicated Fethullah Gulen in the killing, saying the policeman had links to his movement.

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In a video address made available to The Associated Press, Gulen accused the Turkish government of blaming and defaming his movement and suggested the government would facilitate other assassinations and blame them on his followers.

Gulen said "it is not possible for them to convince the world of such accusations."

Russia flew a team of 18 investigators and foreign ministry officials to Turkey to participate in the investigation.

Foreign ministry officials and members of parliaments have gathered at the Russian foreign ministry's headquarters for a farewell ceremony. Diplomats and officials laid flowers at the open casket with an honorary guard standing by.

"Those who raised a hand against Ambassador Karlov, who took his life will definitely fail in their attempts to stop Russia from cooperating with other countries including Turkey," Konstantin Kosachev, chairman of the foreign affairs committee at the upper chamber of the Russian parliament.

President Vladimir Putin is due to attend too. Karlov will be laid to rest in Moscow later Thursday.