Foreign Secretary William Hague has urged remaining Britons to flee a Congolese city after Rwandan-backed rebel fighters arrived on its outskirts.
Mr Hague said the "rapidly deteriorating security and humanitarian situation" in eastern Democratic Republic of the Congo (DRC) meant it was too dangerous to remain in Goma.
More than 150 rebels and two soldiers have been killed since intense fighting broke out on Thursday between the 23 March Movement (M23) and the Congolese army.
BreakinAn M23 spokesman was reported to have said his forces were ready to take the provincial capital, which is a centre for aid operations in the region.M
Only a handful of Britons are believed to remain in Goma but Mr Hague said they should now leave. "I strongly condemn the M23's advance towards Goma and call on it immediately to desist from further violence," he said on Sunday night in statement.
"I am particularly concerned by the risk to civilians, the population of Goma and refugees in surrounding areas. I urge those with influence over M23 to call on them to stop fighting and not to provide them any external support.
"I call for a cessation of hostilities and for all parties to engage to resolve this crisis without further bloodshed. Any British nationals in Goma should leave."
Travel advice on the FCO website advises against all travel to eastern and north eastern parts of the country apart from Bukavu where "essential" travel is not precluded.
A spokeswoman said: "Most of the British nationals registered with our embassy in Kinshasa as residing in Goma have now left, and our embassy has been in close contact by e-mail and phone with those remaining British nationals in the area."