The prime minister also said he was working to ensure British citizens who are still stuck in the country are safe - as they appealed for help getting out.

Mr Sunak said the evacuation of UK diplomats and their dependents was "complex and rapid" and it came amid threats to embassy staff in the capital Khartoum.

British nationals in rescue plea - latest Sudan updates

More than 1,200 British personnel from 16 Air Assault Brigade, the Royal Marines and the RAF were involved in the "difficult operation".

Mr Sunak said he was "continuing to pursue every avenue to end the bloodshed" as he urged the warring sides to lay down their arms and "implement an immediate humanitarian ceasefire to ensure civilians can leave conflict zones".

The British embassy in Khartoum has temporarily been closed as Foreign Secretary James Cleverly said UK diplomats were unable to carry out their functions because of the violence. He said they would be redeployed at other missions in the area.

He said a "temporary lull" in the fighting had allowed UK armed forces to get the officials out.

But Britons are making pleas to be taken out of the country so they escape the fighting.

Mr Cleverly said: "The safety and protection of British nationals in Sudan remains a priority for us - a top priority for us - and we will discharge that duty through our embassies based in the area in close coordination with our international friends and partners."

He warned that until the conflict ends "we are severely limited in our ability to provide assistance to British nationals. I would say to British nationals in the region please register with us".

William, a British national in Khartoum who has been in the country for six years, told Sky News: "I'm sitting in my chair in my living room, listening to a background of shooting probably 3km away."

"I'm as safe as anybody can be in Khartoum at the moment."

'We need to get out'

He added: "The end game is here now. We feel we need to get out. We're very concerned there is nothing happening [in terms of an evacuation plan] it seems. We don't know if this is some wonderful cunning plan that the British government is pursuing.

"It is an extremely concerning situation that's deteriorating further and further. And the imperative is to get out of Khartoum.

"The favourite route seems to be over land towards Egypt but otherwise we haven't got any way of doing that at the moment."

"We're getting absolutely no help at all [from the Foreign Office]."

"This is - by a factor of 10 - the most dangerous situation I have ever been in, no doubt."

"What I need most is to hear that there is a plane somewhere outside of Sudan already and as soon as the airport [in Khartoum or elsewhere] is secured… that plane will come swooping in, we'll get a message saying get to this point and then we'll get on the plane and we'll fly home."

It comes as France, the Netherlands, Belgium and other allies were getting their diplomats and citizens out, hours after US special forces airlifted all American staff from their embassy in Khartoum.

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Here's what's happening on the ground

On Saturday, about 70 American nationals were flown from a landing zone at the embassy to an undisclosed location in Ethiopia, an unnamed US official said.

But the White House said it has no plans for a government-coordinated evacuation of American citizens trapped there.

The US embassy said "due to the uncertain security situation in Khartoum and closure of the airport, it is not currently safe to undertake a US government-coordinated evacuation of private US citizens".

Hundreds dead in past week

According to the World Health Organization, fighting between forces loyal to two top generals has killed more than 400 people since erupting on 15 April.

The violence has included an unprovoked attack on a US diplomatic convoy and numerous incidents in which foreign diplomats and aid workers have been killed, injured or assaulted.

An estimated 16,000 US citizens are registered with the embassy as being in Sudan, although that figure is probably inaccurate because there is no requirement for Americans to register or notify the embassy when they leave.

The conflict between the armed forces, headed by General Abdel Fattah al Burhan, and the Rapid Support Forces (RSF), led by General Mohammed Hamdan Dagalo, has derailed Sudan's transition to democratic rule after decades of dictatorship and civil war.

The fighting broke out in Khartoum and other parts of the country four years after long-ruling autocrat Omar al Bashir was toppled during a popular uprising.