A mission to evacuate Britons from Sudan has begun - as around 4,000 UK passport holders remain stranded amid heavy fighting.
RAF planes will fly into an airfield outside Khartoum and priority will be given to families with children, the elderly and people with medical conditions.
It appears to be race against time as there are fears over whether a 72-hour ceasefire - which began late on Monday - will hold.
Evacuation effort begins for stranded Britons - Sudan latest
Around 1,400 military personnel are believed to be involved.
Prime Minister Rishi Sunak tweeted that RAF aircraft were involved in the "large-scale evacuation" and called it a "complex operation".
The foreign secretary said trapped Britons in Suda are being contacted directly - and they are being told not to go to the airfield unless called.
"The situation remains volatile and our ability to conduct evacuations could change at short notice," said the Foreign Office.
About 4,000 UK passport holders are thought to be trapped in the east African country as rival military factions battle for control.
Hundreds of people have died since the fighting started on 15 April and the evacuation comes after days of pressure for a plan to get Britons out.
Sky's Alistair Bunkall saw an evacuation flight take off from RAF Akrotiri in Cyprus just before 7am and said many more are likely to follow.
The Foreign Office said it is also looking at other potential "points of exit" - possibly by sea, according to Bunkall.
Some UK citizens have manged to escape on evacuation flights operated by other countries.
Germany, Italy, Spain and France are among those that already rescued hundreds of people from dozens of countries on their own flights.
However, the Foreign Office said only British passport holders could get a seat on the UK planes.
