A tiny British subject reconnaissance squad is successful Sudan to see evacuation options, arsenic unit builds connected the authorities to rescue much UK nationals.
Defence curate James Heappey confirmed troops are determination - but nary evacuation program has yet been announced.
On Sunday, the UK airlifted diplomats and their families retired of Sudan successful a subject operation.
But thousands of UK passport holders stay successful the country, wherever hundreds person died amid thoroughfare weapon battles.
Violence broke retired connected 15 April, chiefly successful the superior metropolis Khartoum, betwixt rival subject factions battling for power of Africa's 3rd largest country.
Around 4,000 UK citizens are thought to beryllium successful Sudan and 2,000 of them person already requested help, Foreign Office curate Andrew Mitchell told MPs connected Tuesday.
Hundreds of radical person been airlifted from Sudan by different countries, including much than 1,000 radical by European Union nations. Five British radical were among astir 200 radical evacuated by Saudi Arabia.
Some UK nationals have said they felt abandoned by the government.
Amar Osman, a British national from Dunfermline successful Fife, told the BBC helium feared his household would dice successful Sudan unless they could get themselves retired aft becoming trapped northbound of the capital.
"It's getting worse by the minute, truthful we're reasoning of evacuating by roadworthy to Egypt," said Mr Osman, who was visiting relatives erstwhile warring began.
"I'm doing it each by myself. I'm getting the wealth together, I'm getting each my household together. There's six of us."
News of a 72 hr ceasefire owed to travel into effect from midnight connected Tuesday volition rise hopes that a wide evacuation whitethorn beryllium much feasible, but erstwhile agreements betwixt the warring parties person failed to hold.
The BBC understands a tiny subject squad landed successful Port Sudan, much than 500 miles from Khartoum, to asses imaginable routes out.
Work is nether mode to supply the premier curate with respective options, defence sources said, and it is understood 2 Royal Navy ships are already successful the portion - the frigate HMS Lancaster which was already astatine sea, and proviso vessel RFA Cardigan Bay which is successful Bahrain wherever it was undergoing maintenance.
Mr Mitchell urged anyone trapped successful Sudan to enactment indoors wherever imaginable but to "exercise their ain judgement astir whether to relocate", adding they "do truthful astatine their ain risk".
He told the Commons that Khartoum's main airport, wherever determination has been warring successful caller days, was "out of action". Energy and communications were disrupted, portion nutrient and h2o were becoming "increasingly scarce", helium said.
Defence sources told the BBC immoderate Sudan evacuation would beryllium much hard than the August 2021 Afghanistan airlift, owed to warring astir the superior and an lack of troops already connected the ground.
Khartoum is "more dynamic, much dangerous" than Kabul was astatine the time, they said, with equipped clashes happening "in the neighbourhoods wherever occidental nationals are astir heavy concentrated".
Commenting connected the proposal being issued to radical trapped successful Sudan, the defence root added: "If you archer radical to enactment astatine location they whitethorn beryllium little apt to get shot. But the availability of nutrient and h2o successful the metropolis is progressively limited.
"If you archer radical to permission location it's towards safety. Then they get person to nutrient and h2o but they mightiness beryllium astatine accrued risk."
Responding to questions from MPs, Mr Mitchell besides confirmed that neither the UK's ambassador to Sudan nor the lawman caput of ngo were successful the state erstwhile the struggle began.
A squad of 200 officials is moving astir the timepiece successful the Foreign Office to supply consular assistance to those who request it, and regular updates are being issued, helium added.
British doc Iman Abu Gargar told the BBC she was capable to permission with the French evacuation due to the fact that Irish passport holders, including her son, were capable to join.
Speaking from Djibouti, which lies to the eastbound of Sudan, Dr Gargar said she felt near down by the UK. She said she was forced to permission her begetter there, adding: "There were lone hard decisions to make. I anticipation no-one has to marque the decisions I had to make."
Some MPs person enactment unit connected the authorities to velocity up efforts, including Alicia Kearns, the Tory chairwoman of the Commons Foreign Affairs Committee, who told the Commons that "time is moving out".
Labour's shadiness curate for Africa, Lyn Brown, said what radical trapped successful Sudan request to perceive "is a wide program connected however the authorities volition enactment those inactive successful information and however they volition pass with them and when".
She added: "Naturally, questions volition beryllium asked astir whether the authorities has learned the lessons of the chaotic Afghanistan withdrawal."
A successful cognition to rescue diplomats and their families was carried retired implicit the weekend, aft weapon battles broke retired astir the embassy successful Khartoum.
The BBC understands that UK peculiar forces troops landed successful Khartoum connected Saturday alongside the US evacuation team.
Military vehicles were utilized to rescue embassy unit and transport them to an airdrome extracurricular the capital, earlier they were flown to Cyprus.
Around 1,200 unit from the Army, Royal Navy and Royal Air Force were progressive successful the rescue, and a C-130 Hercules and Airbus A400M transport craft were used.
Mr Heappey, who holds the equipped forces portfolio successful the MoD, said the embassy rescue ngo "went without a hitch" contempt its complexity but that the "job isn't done".
The concern connected the crushed is astatine times "extremely dangerous", helium said, and the "window successful which the situation is permissive is seldom agelong capable successful which to bash the subject options".
Mr Heappey admitted the UK had been caught retired by the accelerated deterioration successful Sudan, adding: "It is just to accidental that cipher successful the UK authorities nor truly successful the wider planetary assemblage saw warring of this ferocity breaking retired successful the mode that it did."
Around 400 UK nationals successful Sudan clasp lone a British passport, portion astir 4,000 much are dual citizens, Mr Mitchell told the Commons.
Another Cobra gathering - an exigency effect committee made up of ministers, civilian servants and others - was held connected Monday to sermon the situation.
UN secretary-general Antonio Guterres told a gathering of the UN Security Council that the concern successful Sudan was worsening and the state was connected "the borderline of the abyss".
"The unit indispensable stop. It risks a catastrophic conflagration wrong Sudan that could engulf the full portion and beyond," helium said.
Sudan has experienced a adjacent full net outage successful caller days, but BBC Monitoring reported that immoderate connectivity was returning connected Monday night.