Iran backtracked on Saturday by admitting it “unintentionally” shot down the Boeing 737-800 on Wednesday, hours after Iran launched ballistic missiles at two US bases in Iraq to avenge the killing of its top military general in an American airstrike.
Later on Saturday, Ukrainian president Volodymyr Zelenskiy’s office said the black boxes from the jet that was shot down near Tehran would be investigated by French specialists.
Iran has rejected claims it shot down a Ukrainian airliner shortly after it took off from Tehran airport.
French president Emmanuel Macron said France would launch an international probe into the crash.
Most of the 176 victims were Iranian and Canadian, but four were British.
Mr Johnson said: “Iran’s admission that Ukraine International Airlines Flight 752 was shot down by mistake by its own armed forces is an important first step.
“This will be an incredibly difficult time for all those families who lost loved ones in such tragic circumstances. We will do everything we can to support the families of the four British victims and ensure they get the answers and closure they deserve.
“We now need a comprehensive, transparent and independent international investigation and the repatriation of those who died. The UK will work closely with Canada, Ukraine and our other international partners affected by this accident to ensure this happens.
“This tragic accident only reinforces the importance of de-escalating tensions in the region. We can all see very clearly that further conflict will only lead to more loss and tragedy. It is vital that all leaders now pursue a diplomatic way forward.”
Iran has rejected claims it shot down a Ukrainian airliner shortly after it took off from Tehran airport.
A number of other countries called on Iran to help any inquiry into what happened by being open and transparent.
Mr Zelenskiy said: “We insist on full admission of guilt. We expect assurances of readiness for a full and open investigation from Iran, bringing those responsible to justice, repatriation of bodies of the dead, payment of compensation, official apologies through diplomatic channels.”
In several statements released on Saturday, Iran claimed the aircraft had veered off its normal course.
General Amir Ali Hajizadeh, commander of the Revolutionary Guard’s air force, in his explanation about what happened said the Ukrainian jet was mistaken for a cruise missile.
He said it appeared to fly in the direction of an air defence missile system and was consequently “hit at this point”.
Iran TV airs footage purportedly of black boxes from the Ukraine airliner that crashed near Tehran, killing all 176 people on board.
He claimed that he had made requests to Iran’s authorities that the country’s airspace be “clear of all flights” but “it was not done”.
Officials at Ukraine International Airlines said that its flight crew were not warned of any risk to the flight before the plane took off from Tehran on Wednesday.
At a briefing by its president and vice president, the airline also denied suggestions that the passenger jet had veered off its normal course, and said Iranian authorities should have closed the airport.
“If you play at war, you play as much as you want, but there are normal people around who you had to protect,” Vice President Ihor Sosnovsky said.
Our defence correspondent Alistair Bunkall explains what appeas to have happened to the Ukraine Airlines jet. 176 people died in the incident.
“If they are shooting from somewhere to somewhere, they were obliged to close the airport. Obliged. And then shoot as much as you want.”
Canadian prime minister Justin Trudeau said: “Our focus remains closure, accountability, transparency, and justice for the families and loved ones of the victims. This is a national tragedy, and all Canadians are mourning together.
“We will continue working with our partners around the world to ensure a complete and thorough investigation, and the Canadian government expects full cooperation from Iranian authorities.”
Sweden’s prime minister joined with other countries demanding Iran co-operate without any restrictions in the investigation.
Germany’s foreign minister also called on Iran to take appropriate measures following what he called a “catastrophe”.
The Queen issued her condolences to the Canadian people over the crash, telling them the “thoughts and prayers” of her and the Duke of Edinburgh were with them for “such a devastating loss”.
“I extend my deepest condolences to the families, friends and colleagues of all those Canadians, and indeed other nationalities, who died, and to the many others who have been affected by this terrible event,” she added.
On Friday, US Secretary of State Mike Pompeo said the US would take “appropriate actions” should it turn out that Iran shot down the plane.
US President Donald Trump attempted to justify the airstrike on General Qassem Soleimani by saying four US embassies had been at risk of attack.
He spoke amid revelations by US officials that the American military had tried, but failed, to kill another senior Iranian commander on the same day Gen Soleimani was killed.
