“UK armed forces have completed a complex and rapid evacuation of British diplomats and their families from Sudan, amid a significant escalation in violence and threats to embassy staff,” Sunak tweeted.

The prime minister said the government was “continuing to pursue every avenue to end the bloodshed in Sudan and ensure the safety of British nationals remaining in the country.”

Defense mininster Ben Wallace tweeted that UK forces undertook the military operation alongside “the US, France and other allies.”

A UK government spokesperson said: “We thank the armed forces for their bravery in conducting this complex operation under extremely challenging circumstances, and commend the courage and commitment of the UK diplomats and embassy staff.

“The safety of all British nationals in Sudan continues to be our utmost priority.

“We are urging the warring factions to implement an immediate and prolonged ceasefire to allow civilians to leave, and the UK Government will do all we can to ensure the safe passage of our citizens in what remains a very challenging context.

“In the meantime, our advice to British nationals is to shelter in place and contact the Foreign Office to register your location and contact details.”

The UK operation involved more than 1,200 personnel from the army, the Royal Marines and the Royal Air Force, he added.

Ferocious battles between the Sudanese army and a paramilitary group — which has seen fighting with tanks in densely populated Khartoum and air strikes launched by fighter jets — have killed more than 400 people and left thousands wounded.