Iran has admitted it shot down the Ukraine passenger jet, killing around 180 people, in an incident it said was unintentional and the result of human error.

Having initially insisted it had nothing to do with the demise of Ukrainian International Airlines Flight 752, whose downing it blamed on mechanical problems, officials in Tehran have now admitted the plane had been shot down after passing close to a sensitive military site.

Yet, while conceding that it was responsible for Wednesday’s downing of the jet, which happened shortly after Iran responded to the targetted killing of Qassem Soleimani by launching ballistic missiles at two bases in Iraq used by US forces, officials in Tehran also sought to put the blame on Washington’s “adventurism”.

“A sad day. Preliminary conclusions of internal investigation by Armed Forces: Human error at time of crisis caused by US adventurism led to disaster,” Iran’s foreign minster Mohammad Javad Zarif, wrote on Twitter.

“Our profound regrets, apologies and condolences to our people, to the families of all victims, and to other affected nations.”

Iran plane crash: Ukraine Boeing 737 comes down near Tehran Show all 18 1 /18 Iran plane crash: Ukraine Boeing 737 comes down near Tehran Iran plane crash: Ukraine Boeing 737 comes down near Tehran People stand near the wreckage after a Ukrainian plane carrying 176 passengers crashed near Imam Khomeini airport in Tehran ISNA/AFP via Getty Iran plane crash: Ukraine Boeing 737 comes down near Tehran People and rescue teams are pictured amid bodies and debris All 176 people on board a Ukrainian passenger plane were killed when it crashed shortly after taking off, Iranian state media reported ISNA/AFP via Getty Iran plane crash: Ukraine Boeing 737 comes down near Tehran One of the engines State news agency IRNA said 167 passengers and nine crew members were on board the aircraft operated by Ukraine International Airlines Iran Press via Reuters Iran plane crash: Ukraine Boeing 737 comes down near Tehran Rescue teams work at the scene AFP via Getty Iran plane crash: Ukraine Boeing 737 comes down near Tehran Passengers' belongings West Asia News Agency via Reuters Iran plane crash: Ukraine Boeing 737 comes down near Tehran Members of the International Red Crescent collect bodies of victims EPA Iran plane crash: Ukraine Boeing 737 comes down near Tehran Rescue teams work amidst debris AFP via Getty Iran plane crash: Ukraine Boeing 737 comes down near Tehran A relative of a victim reacts at Boryspil International Airport, outside Kiev Reuters Iran plane crash: Ukraine Boeing 737 comes down near Tehran Rescue workers search the scene where a Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran, Wednesday, Jan. 8, 2020. A Ukrainian airplane with more than 170 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Iran plane crash: Ukraine Boeing 737 comes down near Tehran TOPSHOT - People and rescue teams are pictured amid the wreckage after a Ukrainian plane carrying 176 passengers crashed near Imam Khomeini airport in the Iranian capital Tehran early in the morning on January 8, 2020, killing everyone on board. - The Boeing 737 had left Tehran's international airport bound for Kiev, semi-official news agency ISNA said, adding that 10 ambulances were sent to the crash site. (Photo by Rouhollah VAHDATI / ISNA / AFP) (Photo by ROUHOLLAH VAHDATI/ISNA/AFP via Getty Images) ROUHOLLAH VAHDATI ISNA/AFP via Getty Iran plane crash: Ukraine Boeing 737 comes down near Tehran Rescue workers carry the body of a victim of an Ukrainian plane crash in Shahedshahr, southwest of the capital Tehran, Iran, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Iran plane crash: Ukraine Boeing 737 comes down near Tehran Part of the wreckage Iran Press via Reuters Iran plane crash: Ukraine Boeing 737 comes down near Tehran Debris of a plane belonging to Ukraine International Airlines, that crashed after taking off from Iran's Imam Khomeini airport, is seen on the outskirts of Tehran, Iran January 8, 2020. Nazanin Tabatabaee/WANA (West Asia News Agency) via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY WANA NEWS AGENCY West Asia News Agency via Reuters Iran plane crash: Ukraine Boeing 737 comes down near Tehran Rescue workers search the scene where an Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Iran plane crash: Ukraine Boeing 737 comes down near Tehran Rescue team work at the scene where an Ukrainian plane crashed in Shahedshahr, southwest of the capital Tehran, Iran, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP Iran plane crash: Ukraine Boeing 737 comes down near Tehran CORRECTS YEAR - Debris is seen from a plane crash on the outskirts of Tehran, Iran, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying at least 170 people crashed on Wednesday shortly after takeoff from Tehranâ€™s main airport, killing all onboard, state TV reported. (AP Photos/Mohammad Nasiri) Mohammad Nasiri AP Iran plane crash: Ukraine Boeing 737 comes down near Tehran Officials inspect the wreckage EPA Iran plane crash: Ukraine Boeing 737 comes down near Tehran Debris is seen from an Ukrainian plane which crashed as rescue workers search the scene in Shahedshahr, southwest of the capital Tehran, Iran, Wednesday, Jan. 8, 2020. A Ukrainian airplane carrying 176 people crashed on Wednesday shortly after takeoff from Tehran's main airport, killing all onboard. (AP Photo/Ebrahim Noroozi) Ebrahim Noroozi AP

General Amir Ali Hajizadeh, the head of the Iranian Revolutionary Guard's aerospace division, said his unit accepts "full responsibility" for the shootdown. In an address broadcast by state TV, he said that when he learned about the downing of the plane, "I wished I was dead."

He said Guard forces ringing the capital had beefed up their air defences and were at the "highest level of readiness," fearing that the US would retaliate. He said an officer made the "bad decision" to open fire on the plane after mistaking it for a cruise missile.

Iran's president Hassan Rouhani said his country "deeply regrets this disastrous mistake."

"My thoughts and prayers go to all the mourning families. I offer my sincerest condolences," he said, while promising an investigation to identify and prosecute the perpetrators.

The admission by Iran came after leaders of various Western nations, perhaps most powerfully Justin Trudeau of Canada, whose nation lost around 60 citizens, pointed the finger of blame at Iran.

“We have intelligence from multiple sources...the intelligence indicates that the plane was shot down by an Iranian surface-to-air missile,” he said on Thursday.

“This may well have been unintentional.”

Following Iran's admission, Mr Trudeau said his government expects “full cooperation from Iranian authorities” in investigating the incident.

Precisely what impact the admission from Iran will make to a situation already beset by distrust and suspicion, remains to be seen.

Iran's ambassador to the UK, Hamid Baeidinejad, issued an apology on Saturday for his initial statements denying Tehran's responsibility for the incident. Mr Baeidinejad had said that Iran was "confident from our side that there has been no missile launched in that area at that time".

Following Iran's admission he tweeted: "In my statement yesterday to the UK media, I conveyed the official findings of responsible authorities in my country that missile could not be fired and hit the Ukrainian plane at that period of time. I apologise and regret for conveying such wrong findings."

It comes as Donald Trump on Friday doubled down on his insistence that the killing of Soleimani – the incident that presaged the downing of the jet – had been necessary.

As Democrats and other critics questioned claims from the Trump administration that Soleimani was plotting “imminent” attacks on US interests, he told Fox News that four US embassies had been at risk, including the one in Baghdad.

It was in Baghdad that the 62-year-old Iranian military leader, was assassinated last week by a US airstrike, carried out by a Reaper drone.

Iran TV footage allegedly shows black boxes from Ukrainian plane that crashed near Tehran

Iran said the passenger plane, en route to Ukraine’s capital Kiev and carrying 167 passengers and 9 members of crew, including 82 Iranians, at least 57 Canadians, 11 Ukrainians and 4 Britons, had been struck “unintentionally“ by its nation’s military.

A statement from the military, and carried by state media, said the plane was mistaken for a ”hostile target“ after it turned towards a ”sensitive military centre“ of the Revolutionary Guard. The military was at its ”highest level of readiness”. it said, amid the heightened tensions with the United States.

“In such a condition, because of human error and in a unintentional way, the flight was hit,” the statement said. It apologised for the disaster and said it would upgrade its systems to prevent future tragedies.

It also said those responsible for the strike on the plane would be prosecuted.

The jetliner, a Boeing 737 operated by Ukrainian International Airlines, went down on the outskirts of Tehran shortly after taking off from Imam Khomeini International Airport.

”This is the right step for the Iranian government to admit responsibility, and it gives people a step towards closure with this admission,“ said Payman Parseyan, a prominent Iranian-Canadian in western Canada who lost a number of friends in the crash.

“I think the investigation would have disclosed it whether they admitted it or not. This will give them an opportunity to save face.”