The first evacuation flight of 40 UK nationals from Sudan has landed in Cyprus.
It's estimated around 4,000 UK passport holders are stranded in the east African country after fighting broke out earlier this month between the Sudanese army and rebel Rapid Support Forces.
Around 2,000 have registered for evacuation, with Prime Minister Rishi Sunak saying the next 24 hours were "absolutely critical" as two more flights are expected to rescue more stranded Brits overnight.
Sunak added: "We can make a big push as we're already doing and you can help us get everyone who wants to come home, home."
It's understood the RAF are working within a 24 hour window ceasefire to get planes in and out of Sudan.
The first rescue flight saw an RAF plane collect people from an airfield near Khartoum, with priority being given to families with children, the elderly and vulnerable.
UK nationals are being flown to Larnaca International Airport in Cyprus before being transported back to the UK.
Brits are however having to make their own way to the airfield, negotiating checkpoints and potential outbreaks of fighting.
Around 1,400 military personnel are believed to be involved in the UK operation.
UK defence secretary Ben Wallace told Channel 4 news "we can take, really, who turns up at the moment" - adding "there is some risk that some of the planes are not full".
Only British passport holders and their immediate family with existing UK entry clearance are eligible, the government has said.
However, the BBC reports many British nationals have spent days indoors with food and drink running low and no electricity.
Several have spoken of their anger and desperation at being left behind, while other foreign nationals and UK embassy staff were flown out.
Foreign Secretary James Cleverly said: "The UK Government is co-ordinating an evacuation of British nationals from Sudan.
"We have started contacting nationals directly and providing routes for departure out of the country."
The Foreign Office said other exit routes are being considered, with two British military ships - RFA Cardigan Bay and Type 23 frigate HMS Lancaster - being lined up for possible evacuations.
The Foreign Office stressed that "senior diplomats" will be supporting the evacuations, after it emerged that British Ambassador to Sudan Giles Lever and his deputy were out of the country when violence broke out in Khartoum.
One British doctor stranded in Sudan has fled to the Egyptian border with her three kids after UK officials took “too long” to evacuate Brits.
Gynaecologist Dr Lina Badr made the terrifying dash from Khartoum with her son, aged two, and daughters, 12 and 15, after the family home they were hiding in was struck by a missile.
The medic from Birmingham sent desperate messages home after she got trapped amid the conflict while on an annual holiday celebrating Eid with family.
But, with little information from UK officials and escalating violence, she made the decision to flee to the border, arriving on the day RAF planes finally launched an evacuation effort.
In a message to a friend she said: “Sadly, I have completely lost hope in the system...the UK Government response has been 12 days too long, forcing us civilians to risk our lives.”
Her friend Ruksana Shain said Dr Badr was still in distress, her family now among thousands of people crowding at the Egypt border trying to get home.
“There are no facilities, no food, some people have been stuck there for days. It is a terrible situation,” she said.
Dr Badr’s husband, Ousama Suliman, 45, said his family was “petrified” after fighting erupted in the Al Amarat area of Khartoum where they were staying.