The crash of a Ukrainian passenger jet was a tragedy arising from the supercharged tensions of the Middle East and could have been avoided, an expert said following Iran's admission that it "unintentionally" shot down the jet with missiles.

Iranian President Hassan Rouhani said on Saturday that a military probe into the tragedy had concluded that "missiles fired due to human error" brought down the Boeing 737-800. He called it an "unforgivable mistake".

The acknowledgment came days after the Wednesday crash, which killed all 176 people on board. Teheran first denied the possibility of human error and said the crash was the result of a technical problem.

Iran's assignment of blame to human error was reasonable, given the overall context, said Li Shaoxian, a Middle East studies expert at Ningxia University.

The missiles struck the jet just a few hours after an Iranian missile strike against two United States military facilities in Iraq.

"It sounds reasonable that the Iranian military made the mistake because of the high tension. The Iranians had no idea how the US would react to the military strike," he said. Commanders at the front line had authority to launch missiles against any suspicious targets.

The General Staff of the Iranian Armed Forces said on Saturday that the Ukraine flight "resembled a hostile target approaching a sensitive center" of the Islamic Revolutionary Guards Corps, especially "under sensitive and critical conditions" when US aircraft flights had increased near Iran's borders.

Li described the tragedy as the unexpected product of high tension in the Persian Gulf region and Iran's high alert for attacks. A war mentality, he said, was rooted in the US assassination of Iranian General Qasem Soleimani in Iraq on Jan 3.

"Without the assassination, there would be no high tension in the regional situation," Li said. "The US bears responsibility for this situation and the painful accident."

He called the shooting down of the aircraft "a freak".

"It shouldn't have happened. This is why all parties, including China, have been urging the US and Iran to de-escalate and maintain restraint," he said.

British Prime Minister Boris Johnson said on Saturday that the tragic accident "only reinforces the importance of de-escalating tensions in the region".

"It is vital that all leaders now pursue a diplomatic way forward," he said. "We can all see very clearly that further conflict will only lead to more loss and tragedy."

In his statement, Rouhani apologized for the catastrophe and extended condolences to the families of the victims. He also promised to investigate further to "identify all the causes and roots" and prosecute anyone who may have acted inappropriately.

After a conversation with Rouhani, Ukrainian President Volodymyr Zelensky said on Twitter that acknowledging the missile strike was "a step in the right direction".

"I insist on the immediate completion of identification of the bodies and their return to Ukraine," Zelensky said. "The perpetrators must be held accountable."

Rouhani said joint investigations between the Iranian and Ukrainian experts will continue, and judicial measures will start "soon".

In a phone conversation with Canadian Prime Minister Justin Trudeau, whose country had 57 citizens on board, Rouhani said he welcomed cooperation within the framework of international regulations that is aimed at clarifying the dimensions of the incident.

Li, the expert at Ningxia University, said Iran's acknowledgment should have come earlier, but it was still a wise and necessary move that could help in a difficult time.

"The series of measures, from acknowledging the mistake to promising investigation and compensation, can build some trust in the international community, as well as eliminate some misunderstandings," he said.

Meanwhile, on Friday, the US imposed fresh sanctions on Iran despite international calls for restraint. The sanctions cover metal manufacturing and other sectors of the Iranian economy.

Reuters—AFP—Xinhua