The United Nations Security Council will hold an emergency session over the killing of Hamas political bureau leader Ismail Haniyeh in Iran's capital Tehran on Wednesday, Russia said.

The meeting, requested by Iran and supported by representatives of Russia, China and Algeria, is scheduled for 4:00 p.m. (2000 GMT), said a spokesman for the Russian presidency, which holds the rotating leadership of the council.

Iran's permanent mission to the U.N. on Wednesday called for an urgent meeting of the UNSC.

A letter was sent to Vassily Nebenzia, the permanent representative of Russia and the current president of the U.N. Security Council, and described the killing of Haniyeh as a "terrorist attack and an act of aggression on the sovereignty and territory."

In the letter, Iran strongly condemned the "aggressive action of the Zionist regime" in the assassination of Haniyeh, characterizing the "terrorist act" as part of the assassinations of Palestinian resistance leaders and the genocide against Palestinians.

Emphasizing the role of the U.S. as the strategic ally and supporter of the Israeli regime, the letter said: "This act could not have occurred without the authorization and intelligence support of the U.S."

The letter called for decisive action from the international community and the U.N. Security Council to punish the perpetrators, requesting an emergency meeting of the council.

"In light of these grave consequences of Israeli criminal acts on regional peace and security, the Islamic Republic of Iran calls upon the United Nations Security Council to condemn unequivocally and strongly the acts of aggression and terrorist attacks by the Israeli regime on Iran's sovereignty and territorial integrity, as well as recent acts of aggression," the letter noted.

It also urged the U.N. Security Council to consider sanctions and other measures to punish Israel for its violations of international law.

Haniyeh was in Tehran to attend the inauguration ceremony of new Iranian President Masoud Pezeshkian on Tuesday.

Haniyeh was reelected as the head of the Hamas political bureau in 2021 for a second consecutive term, slated to end in 2025.

Early Wednesday, the Palestinian resistance group Hamas announced that Haniyeh was killed in an Israeli airstrike in Tehran.

Israel has not yet confirmed or denied its involvement.

The killing of Haniyeh came as Israel continued its devastating military campaign in the Gaza Strip which has killed more than 39,400 victims and injured over 91,000 since Oct. 7 following an attack by Hamas.