"We can confirm that a British national residing in Sierra Leone has tested positive for Ebola virus infection," Xinhua quoted the health department as saying.
It said that medical experts are assessing the situation to ensure that appropriate care is delivered, and consular assistance is being provided.
"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," said John Watson, deputy chief medical officer.
"We have robust, well-developed and well-tested NHS (National Health System) for managing unusual infectious diseases when they arise, supported by a wide range of experts," he added.
The outbreak of Ebola began in the forested zone on the borders of Guinea, Sierra Leone and Liberia earlier this year, and spread to Nigeria last month. The disease has already killed over 1,300 people.