TEHRAN, Iran

Iran’s attorney general has ordered a probe into the assassination of Hamas political chief Ismail Haniyeh in the wee hours of Wednesday morning in north Tehran.

In an order published in local media, Mohammad Movahedi Azad instructed the Public Prosecutor of Tehran to assign a special investigative branch to “examine all aspects of the incident.”

Haniyeh, who was in the Iranian capital to attend the swearing-in ceremony of the newly elected President Masoud Pezeshkian, was assassinated in an attack on his residence in northern Tehran.

According to Iranian media, the attack targeted a guesthouse for war veterans managed by the Islamic Revolutionary Guard Corps (IRGC) where the visiting Hamas leader was staying.

The IRGC confirmed the assassination of Haniyeh and one of his bodyguards in the mysterious attack and said an investigation into the incident was currently underway.

While Hamas and Iran blamed Israel for the assassination, Tel Aviv has not confirmed or denied its involvement.

The attorney general extended his condolences to the Palestinian people, Haniyeh’s family and Hamas members, and condemned what he called the “horrific crime.”

He said the attack was committed within the territory of the Islamic Republic of Iran, “in breach of well-established principles of international law.” He called it a “sign of the depravity and baseness of its perpetrators and instigators.”

He ordered the prosecutor to investigate the incident “in cooperation with military, law enforcement, and security forces.”

“They must appropriately address any possible negligence or fault and utilize all domestic and international capacities with a firm resolve to arrest, prosecute, and punish the individuals responsible for this terrorist act,” he said in the order.

Iran has declared three days of national mourning following the assassination of the Hamas leader, saying it has “caused grief to the Islamic nation, the devotees of the resistance movement, and all the free people of the world.”

Earlier in the day, Iran's Supreme Leader Ayatollah Ali Khamenei in a statement said the country considers it a duty to “avenge the dear guest's blood,” vowing “severe punishment.”

President Pezeshkian also condemned the assassination of the Hamas leader, pledging to "defend the country's territorial integrity, honor and dignity."

It remains to be seen how and when Iran plans to retaliate, with experts saying all options would be on the table after the IRGC completes its initial probe into the incident.