This article is more than 8 months old

This article is more than 8 months old

Australian prime minister Scott Morrison has backed other western leaders including Donald Trump, Justin Trudeau and Boris Johnson in alleging Iran accidentally shot down a passenger jet in Tehran shortly after a volley of missile fire aimed at US military bases in the region.

Intelligence sources told the Guardian their assessments suggest two surface-to-air missiles had targeted the Boeing 737-800 passenger jet that crashed in Iran on Wednesday morning, killing all 176 people onboard.

Morrison told reporters in Canberra: “Australia has received similar intelligence to … Canada and from out of the United States… all of that intelligence presented to us today does not suggest an intentional act.”

A visual guide to the Iran plane crash Read more

Morrison said a full and independent inquiry into the incident was needed, and the black boxes from the plane – which Iran is currently refusing to release – should be made available to investigators outside of Iran.

“It’s absolutely critical that a full and transparent investigation is undertaken into this terrible event and that would include undertaking all efforts to ensure we get recovery of the black box recorder that can obviously inform that investigation.”

Morrison’s comments follow those of Canadian prime minister Justin Trudeau who said his country “will not rest” until it got justice for the loss of Canadian lives.

Of the 176 people onboard, 79 were Iranian, 63 were Canadian and 11 were Ukrainian (including nine crew members), along with 10 Swedes, seven Afghans, three Britons and three German nationals.

“We have intelligence, including from our allies and own intelligence that the plane was shot down by Iranian surface-to-air missiles,” Trudeau said. “Canadians want answers. That means transparency, accountability and justice.”

Play Video 'I want answers': Justin Trudeau says missile downed plane in Iran – video

Ukraine International Airlines flight 752 aircraft crashed in farmland on the outskirts of Tehran a few hours after Iran had fired more than a dozen missiles at US bases in Iraq. Commanders of Iran’s Revolutionary Guards have said that in the hours after the missile strikes, they were on high alert, anticipating an imminent American response.

The Iranian missile strikes were retribution for the US assassination, by reaper drone, of Iran’s most powerful general Qassem Soleimani, in an attack at Baghdad airport last week.

Australia is part of the Five Eyes intelligence-sharing network – along with the US, UK, Canada and New Zealand – that cooperates on intelligence measures, and so will have seen the same intelligence material its allies have.

The black boxes from the flight have been found and secured by Iranian authorities who say they will not share them with US aviation authorities or with the aircraft manufacturer, Boeing, but will give Ukrainian investigators access to the investigation.

The UK prime minister, Boris Johnson, said there was now a “body of information” that the flight was shot down by an Iranian surface-to-air missile.

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“This may well have been unintentional. We are working closely with Canada and our international partners and there now needs to be a full, transparent investigation.”

The US president, Donald Trump, said he had “suspicions” the plane had been accidentally shot down.

“Someone could have made a mistake on the other side,” he said. “Some people say it was mechanical, I personally don’t think that’s even a question. I have a feeling that … something very terrible happened.”

Iran has fiercely rejected the uniform western intelligence assessments.

“Scientifically, it is impossible that a missile hit the Ukrainian plane, and such rumours are illogical,” Ali Abedzadeh, the head of Iran’s of Civil Aviation Organisation told state-run media.

Morrison confirmed earlier this week Australian troops would remain in Iraq. Operation Okra comprises a special operations task group, as well as task group Taji, which works to train Iraqi security forces.

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Taji is based at the Taji military base, about 30km north of Baghdad. The base was not targeted this week, despite early reports it had been. The base did close operations during the week.

As Iraq’s security situation has deteriorated dramatically over the past few months, Iraqi interpreters working alongside Australian diggers have raised concerns that they will be targeted by Iranian-backed militias who have publicly threatened Iraqi nationals who support foreign forces.

Interpreters have told the Guardian they fear they will be abandoned if Australian troops are forced to leave Iraq, and say they are being practicably prevented from applying for visas.