Boris Johnson has said assassinated Iranian general Qassem Soleimani had the “blood of British troops on his hands”.
But the prime minister told MPs on Wednesday he opposed any further escalation of violence in the Middle East.
Last night Iran struck back at the United States for the killing of Soleimani by firing ballistic missiles at two military bases in Iraq that house American troops.
In his first public appearance since the US strike, Johnson said America had the right to defend its bases.
“Clearly the strict issue of legality is not for the UK to determine since it was not our operation,” the prime minister said during PMQs.
“But I think most reasonable people would accept that the United States has the right to protect its bases and its personnel.”
The PM said Soleimani had supplied “improvised explosive devices to terrorists, which I’m afraid killed and maimed British troops”.
Johnson said: “That man had the blood of British troops on his hands.”
He added: “As far as we can tell there were no casualties last night sustained by the US and no British personnel were injured in the attacks.”
Jeremy Corbyn accused Johnson of being “unable to stand up to President Trump” over Iran, because he had “hitched his wagon to a trade deal with the United States”.
The Labour leader’s spokesperson said the assassination of Soleimani was “clearly illegal” unless there was evidence of imminent attack.
“The issue is not the record of Qassem Soleimani inside or outside Iran, the fact is that he was a top ranking government official of an internationally recognised government who was killed by the US in a third country and that is clearly illegal in international law,” the spokesperson added.
“The only circumstances in which it could be justified legally is if there was evidence of imminent threat to US forces under the control of Soleimani. There’s no such evidence been produced.”
Iran’s missile attack was a major escalation between the two long-time foes and Iran’s most direct assault on America since the 1979 seizing of the US embassy in Tehran.
Iranian state TV said it was in revenge for the killing of Soleimani last week in an American drone strike near Baghdad.
US and Iraqi officials said there were no immediate reports of casualties, though buildings were still being searched. The Iraqi government later confirmed there were no casualties among Iraqi forces.
Donald Trump tweeted “all is well!” shortly after the missile attacks, adding: “So far, so good” regarding casualties.