The first foreign citizens were evacuated from battle-scarred Sudan on Saturday, as witnesses described the streets of Khartoum as being filled with the "stench of blood".

In the first extraction of civilians, a boat carrying 50 Saudi Arabians arrived in Jeddah, where four more ships carrying over 100 people from 11 countries were expected later on Saturday.

The initial evacuees included the crew of a Saudi passenger plane that was hit by gunfire as it tried to take off from Khartoum at the start of the fighting on April 15.

With the airport in the Sudanese capital caught in the violence, Western nations have been unable to evacuate embassy staff safely.

Sudan's army said the United States, Britain, France and China had been in touch about evacuating their diplomatic staff, and it had "agreed to facilitate evacuations of foreign nationals" using those countries' military aircraft.

There was no confirmation from the Western countries of an impending evacuation.

Rishi Sunak, the Prime Minister, held an emergency Cobra meeting on the crisis which included Ben Wallace, the Defence Secretary, and Andrew Mitchell, the Africa minister.

A government spokesman said: "We recognise that the situation is extremely concerning for British nationals trapped by the fighting in Sudan.

"We are doing everything possible to support British nationals and diplomatic staff in Khartoum, and the Ministry of Defence is working with the Foreign Office to prepare for a number of contingencies."

British citizens in Sudan have been advised to register with the embassy and to stay indoors, after skirmishes broke out in residential areas when a fragile ceasefire agreed on Friday night broke down within hours.

Joe Biden approved a plan for the Pentagon to move additional troops, including US Marines, to its base in Djibouti ahead of a possible evacuation of US embassy personnel.

There are an estimated 16,000 US citizens trapped in Sudan, and the White House said it was "pre-positioning some additional capabilities nearby in case that they're needed".

Mr Sunak spoke on Friday with Ismail Omar Guelleh, the president of Djibouti. Flight-tracking websites showed US, British, French and German military aircraft heading there.

Members of the South Korean Air Force departed for the region, and Japan was also deploying forces nearby.

Jordan said it had already started arranging for the repatriation of its citizens stuck in Sudan, and was coordinating its efforts with Saudi Arabia and the United Arab Emirates.

The situation in Sudan has been deteriorating as fighting between the forces of rival generals in Khartoum entered a second week.

Clashes erupted between forces loyal to Abdel Fattah Burhan, the head of the army, and those of his former ally Mohamed Hamdan Daglo, known as Hemedti, who heads the paramilitary Rapid Support Forces [RSF].

The RSF is a force tens of thousands strong formed from members of the Janjaweed militia.

Burhan and Hemedti seized power in a coup in 2021 but later fell out in a bitter power struggle.

On Saturday, heavy gunfire, loud explosions, and fighter jets roared over Khartoum.

Resident Sami al-Nour said: "Gunfire and the stench of blood all around us."

The RSF said it was ready to "partially" open "all airports" in Sudan to evacuate foreign citizens.

Meanwhile, Burhan told Al-Arabiya TV that his army was in control of "all airports except for Khartoum" and one in Nyala, the capital of South Darfur.

He said Khartoum’s airport would not be used for evacuating foreigners because of the ongoing fighting.

He said: “We share the international community's concern about foreign nationals. Living conditions are deteriorating.

“No one can predict when and how this war will end. I am currently in the command centre and will only leave it in a coffin."

The extent of the damage at the Khartoum airport remained unclear, but one runway has been damaged and planes have been wrecked by shelling and air strikes.

According to the World Health Organisation, 413 people have been killed and 3,551 injured in the fighting across Sudan so far, but the actual death toll is thought to be higher.

The World Food Programme has warned that the violence could plunge millions into hunger.