Iranian President Masoud Pezeshkian said the Islamic Republic considers avenging the killing of Supreme Leader Ayatollah Ali Khamenei a "legitimate right" and pledged to pursue those responsible with the country's full capabilities, Ettelaat newspaper reported on March 1.

In a formal condolence message, Pezeshkian described the assassination of Iran's highest-ranking political and religious authority by what he termed the "accursed American-Zionist axis" as an "open declaration of war against Muslims, especially Shia communities across the world."

"The Islamic Republic of Iran considers seeking retribution against the perpetrators and those who ordered this historic crime to be its duty and legitimate right, and will devote all its power to fulfilling this great responsibility," Pezeshkian said in the statement carried by the state-run daily.

The president called Khamenei's killing "the greatest affliction facing the Islamic world today" and praised 37 years of leadership in which Iran became what he described as a centre of resistance against global arrogance.

"Truly, nothing but martyrdom on the battlefield against the enemies of Islam was befitting of the name and station of Grand Ayatollah Ali Khamenei," his official statement said. 

Pezeshkian reaffirmed his "unwavering determination" to continue Khamenei's path and called on Iranian officials and citizens to unite in pursuit of the Islamic Revolution's goals.

The statement came as Iran's temporary Leadership Council — comprising Pezeshkian, Chief Justice Gholamhossein Mohseni Ejei and newly appointed Guardian Council jurist Ayatollah Alireza Arafi — assumed the supreme leader's duties pending the Assembly of Experts' selection of a permanent successor.

Iran declared 40 days of national mourning and seven days of public holiday following the confirmation of Khamenei's death in the joint US-Israeli strikes on Tehran on February 28.