File Photo: Ethiopian government soldiers ride in the back of a truck on a road near Agula, north of Mekele, in the Tigray region of northern Ethiopia on Saturday, May 8, 2021.
"The conflict in Ethiopia is deteriorating quickly," Africa minister Vicky Ford said.
"In the coming days, we may see fighting move closer to Addis Ababa, which could severely limit options for British nationals to leave Ethiopia," she said.
"I am urging all British nationals_whatever their circumstance_ to leave immediately while commercial flights are readily available and (the airport) remains open."
Britain has been advising its citizens to leave Ethiopia since November 9 due to the worsening conflict between the government and the rebels.
Foreign, Commonwealth and Development Office travel advice currently warns that the fighting "has potential to escalate and spread quickly and with little warning".
London has temporarily suspended the requirement for travellers unvaccinated against Covid-19 to test before their arrival in Britain to help those wishing to leave.
The announcement came after Ireland said Ethiopia had expelled four of its six diplomats in the country due to the country's previous comments on the conflict.
Last month, Britain announced a further £29 million ($37 million) in aid funding for people affected by the conflict in northern Ethiopia.
London has also called for an urgent ceasefire to allow humanitarian aid through and for Addis Ababa to lift an effective blockade of relief to the Tigray region.
It also joined more than 40 countries in condemning the expulsion of leading UN representatives from Ethiopia.