A British national living in Sierra Leone has tested positive for Ebola , the Department of Health said.
It is the first confirmed case of a B riton contracting the deadly virus during the recent outbreak. There is no cure for Ebola.
Professor John Watson, deputy chief medical officer, said: " The overall risk to the public in the UK continues to be very low. Medical experts are currently assessing the situation in Sierra Leone to ensure that appropriate care is provided.
"We have robust, well-developed and well-tested NHS systems for managing unusual infectious diseases when they arise, supported by a wide range of experts."
Consular assistance is being provided to the Briton.
The World Health Organisation (WHO) has put the number of people infected with the deadly virus at 2,615. Some 1,427 have died since the disease was identified in Guinea in March and spread to Sierra Leone, Liberia and Nigeria.
Rigorous quarantine measures are used to stop the spread of Ebola, as well as high standards of hygiene for anyone who might come into contact with sufferers.
Symptoms of the virus appear as a sudden onset of fever, intense weakness, muscle pain, headache and sore throat.
According to the WHO, this is followed by vomiting, diarrhoea, rash, impaired kidney and liver function and, in some cases, both internal and external bleeding.
The effects of the disease normally appear between two and 21 days after infection.
It is transmitted to people from wild animals and spreads in the human population through person-to-person transmission. Outbreaks have a case fatality rate of up to 90%.
The WHO says the disease can be passed between people by direct contact - through broken skin or mucous membranes - with the blood, secretions, organs or other bodily fluids of infected people, and indirect contact with environments contaminated with such fluids.
The Foreign and Commonwealth Office (FCO) issued updated travel advice earlier this week which urged people to carefully assess their need to travel to Sierra Leone, Guinea and Liberia.
"General medical facilities throughout Sierra Leone are currently under severe strain due to the Ebola outbreak, and unable to provide the same standard of healthcare as in the UK. Dedicated healthcare facilities for Ebola are overwhelmed," the FCO warned.
The Sierra Leone parliament has voted to pass a new law which means anyone caught hiding an Ebola patient can receive prison terms of up to two years.
Some 910 cases have been recorded in the country - and 392 deaths - but the WHO believes the magnitude of the outbreak has been underestimated because people are hiding infected friends and family in their homes.
In a situation assessment issued yesterday, the organisation warned: "As Ebola has no cure, some believe infected loved ones will be more comfortable dying at home.
"Others deny that a patient has Ebola and believe that care in an isolation ward - viewed as an incubator of the disease - will lead to infection and certain death. Most fear the stigma and social rejection that come to patients and families when a diagnosis of Ebola is confirmed."
The WHO reported that corpses are being buried in rural villages without notifying health officials and with no investigation of the cause of death. In some instances epidemiologists have travelled to villages and counted the number of fresh graves as a rough estimate of suspected cases.
Speaking in parliament, Sierra Leone majority leader Ibrahim Bundu accused development partners of being slow to respond to the crisis and said the country had suffered "abandonment and isolation from those we viewed to be our biggest friends".
"These ugly developments are evidenced in the cancellations of flights, closing of borders, reduction of operational hours of banks and further isolation by shutting down businesses at the time of greatest need," he said.
British Airways suspended flights to Liberia and Sierra Leone on August 5 until the end of the month over concerns about the outbreak.
The carrier normally operates a four-times-a-week service from Heathrow to Freetown in Sierra Leone, with a connection on to Monrovia in Liberia.
It was confirmed yesterday that an Irish engineer who died at home after returning from working in Sierra Leone had not contracted Ebola.
Dessie Quinn, 43, was being treated for malaria after returning two weeks ago from the west African country and was found dead in bed in Co Donegal by a friend in the early hours of Thursday. The Health Service Executive said test samples proved negative for Ebola.