Tehran: Iran on Saturday admitted that its armed forces had downed the Ukrainian passenger plane near Tehran killing all 176 people on board, adding that it was an “involuntary human error” and those responsible would “immediately” be held accountable.

In a statement, the General Staff of the Armed Forces of the Islamic Republic of Iran said that at the time of the accident on Wednesday, the forces had been on the highest alert, according to a report by the Tehran-based Press TV.

It assured that “by pursuing fundamental reforms in operational processes at the armed forces’ level, we will make it impossible to repeat such errors”.

Also issuing a statement, Iran’s Islamic Revolutionary Guard Corps (IRGC) added that the mistake was made in the context of a “very delicate crisis situation”, claiming that the US-made Boeing 737-800 had flown close to a sensitive IRGC military centre with the “altitude and flight position of an enemy target”, reports Efe news.

Reacting to development, President Hassan Rouhani in a tweet said: “The Islamic Republic of Iran deeply regrets this disastrous mistake. My thoughts and prayers go to all the mourning families. I offer my sincerest condolences.”

Foreign Minister Mohammad Javad Zarif also offered “profound regrets, apologies and condolences to our people, to the families of all victims, and to other affected nations”.

“A sad day. Preliminary conclusions of internal investigation by Armed Forces: Human error at time of crisis caused by US adventurism led to disaster,” he tweeted.

Saturday’s confirmation comes after the Iranian military had been denying that one of their missiles brought down the the Kiev-bound Ukraine International Airlines (UIA) flight PS75.

The victims comprised 82 Iranians, 63 Canadians, 11 Ukrainians, 10 Swedes, four Afghans, four Britons and three Germans.

A day after the crash, Canadian Prime Minister Justin Trudeau and US media reports, citing American and Iraqi intelligence officials, said that the airliner was shot down by an Iranian missile.

Trudeau said that his government had “evidence” indicating that the aircraft “was shot down by an Iranian surface to air missile”, although he added that it might have been unintentional.

These claims were rejected by Iranian government spokesman Ali Rabiei on Friday, saying that “these reports are a psychological warfare against Iran”.

“All those countries whose citizens were aboard the plane can send representatives and we urge Boeing to send its representative to join the process of investigating the black box.”

Wednesday’s crash occurred on the same day after Iran launched more than a dozen ballistic missiles at two US military bases in Iraq, in retaliation for the killing of Iranian Major General Qasem Soleimani in an American drone attack in Baghdad on January 3.