British Prime Minister Rishi Sunak chaired a meeting of the government's emergency response committee on Saturday to discuss the situation in Sudan, with defence minister Ben Wallace among those attending.
Sudan's army said on Saturday it had agreed to help evacuate foreign nationals, as gunfire and air strikes echoed across Khartoum despite promises by warring sides to cease fire for three days after a week of strife that has killed hundreds.
The army said the United States, Britain, France and China would evacuate diplomats and other nationals from Khartoum "in the coming hours".
"We recognise that the situation is extremely concerning for British nationals trapped by the fighting in Sudan," a government spokesperson said when asked about the comments.
"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."
On Saturday, Britain's Foreign Office updated its travel advice for Sudan to warn that "in the event of a ceasefire, any decision to move must be taken at individual risk".