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Iran on Saturday vowed to take international legal action against Saudi Arabia's rulers over the crush of Muslim pilgrims at this year's hajj, which killed at least 769 people, including 136 Iranians, and has led to an escalation of tensions between the regional archrivals.

The pilgrims suffocated or were trampled to death Thursday when two massive crowds converged on a narrow street, in the worst disaster to occur during the annual pilgrimage in a quarter-century. Shiite Iran has accused Sunni Saudi Arabia of mismanaging the pilgrimage, which annually draws some 2 million people from 180 countries.

RELATED: Death Toll From Hajj Stampede Rises to 769

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Iranians comprise the largest group of casualties identified so far. Iranian state TV says a former ambassador to Lebanon, as well as two Iranian state TV reporters and a prominent political analyst are among those still missing. The semi-official Fars news agency said a former ambassador to Slovenia was among the dead.

"Under international law, this incident is absolutely subject to prosecution. The Al-Saud must be responsive," Iran's State Prosecutor Ebrahim Raisi told state TV, referring to Saudi Arabia's ruling family.

Pakistani mother Sarwari Begum is comforted by her husband, as she cries for her daughter, Bushra Khalique, 27, who is reportedly missing after a crush during the hajj pilgrimage in Saudi Arabia, Saturday, Sept. 26, 2015 in Karachi, Pakistan. Fareed Khan / AP

He said Saudi authorities blocked a road used by hajj pilgrims to allow a royal convoy to pass through, causing the deadly convergence in the town of Mina on the outskirts of Mecca.

"They have to know that we will pursue the trial of Al-Saud for the crime they have committed against the hajj pilgrims through international courts and organizations."

RELATED: Somber Pilgrims Continue Hajj After Stampede 'Catastrophe'

Neither Iran nor Saudi Arabia is a state party to the International Criminal Court, and only the court's prosecutor can file charges. Iran could try to file a case at the International Court of Justice, which handles disputes between nations but does not mete out criminal justice.

Saudi Arabia has not responded to the Iranian accusations regarding the convoy. Saudi Interior Ministry spokesman Maj. Gen. Mansour al-Turki told The Associated Press that a VIP convoy traveling through Mina on Thursday, which included foreign dignitaries, had nothing to do with the incident and was in a different part of town. He said VIPs use their own roads in Mina.