Russia has denounced the Israeli assassination of Hamas political leader Ismail Haniyeh, labeling it an "unacceptable political assassination."

Hamas on Wednesday confirmed that Haniyeh was killed in an Israeli strike on his residence in the Iranian capital, Tehran.

"It is a completely unacceptable political assassination, and this will lead to a further escalation of tensions," Russian Deputy Minister of Foreign Affairs Mikhail Bogdanov told the state-run RIA Novosti news agency.

Konstantin Kosachev, the vice-president of Russia's upper house Federation Council, said he expected a "sudden escalation of mutual hatred in the Near East."

"The most difficult period of confrontations is beginning in the region," he wrote on Telegram.

Russian Foreign Minister Sergei Lavrov welcomed Haniyeh to Moscow in September 2022 for discussions on the Israeli-Palestinian conflict.