Boris Johnson accused executed Iranian general Qassem Soleimani of being "a threat to all our interests" and said "we will not lament his death" as he called for de-escalation from all sides.

After speaking to US President Donald Trump on Sunday, the Prime Minister issued his first statement on the deepening crisis in the Middle East after the US's fatal drone strike on Iran's top military leader.

Mr Johnson warned that all calls for reprisals "will simply lead to more violence in the region and they are in no one's interest" in the wake of the killing in Baghdad on Friday.

Following his return from a holiday in the Caribbean, the UK's prime minister confirmed he has spoken with France's Emmanuel Macron, Germany's Angela Merkel, and US President Donald Trump.

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The PM said he will be speaking to Iraq "to support peace and stability" after its parliament called for the expulsion of foreign troops, including British soldiers working against so-called Islamic State.

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"General Qassem Soleimani posed a threat to all our interests and was responsible for a pattern of disruptive, destabilising behaviour in the region," Mr Johnson added.

"Given the leading role he has played in actions that have led to the deaths of thousands of innocent civilians and western personnel, we will not lament his death.

"It is clear however that all calls for retaliation or reprisals will simply lead to more violence in the region and they are in no one's interest."

Mr Johnson, who was facing criticism for his silence while on holiday in the Caribbean during the escalating crisis, also said he had spoken to French President Emmanuel Macron and German Chancellor Angela Merkel.

Downing Street said the PM arrived back in the UK on Sunday, but did not immediately say whether he was in Number 10.

Ministers are due to meet on Monday to discuss the crisis that has raised fears of all-out war and the Foreign Office will update Parliament on Tuesday.

READ MORE: Boris Johnson criticised for 'sunning himself' in Caribbean as fears over all-out Middle East war grow

A non-legally binding bill passed by Iraq's parliament called for the expulsion of all foreign forces.

A UK Government spokesman said: "The coalition is in Iraq to help protect Iraqis and others from the threat from Daesh (Islamic State), at the request of the Iraqi government.

"We urge the Iraqi government to ensure the coalition is able to continue our vital work countering this shared threat."

In response to the killing of Gen Soleimani on Friday, Iraqi prime minister Adel Abdul-Mahdi said the parliament could end the presence of foreign troops or restrict their mission training local forces. He backed the first option.