A doctor who recently returned to France from a humanitarian mission in the Democratic Republic of Congo has tested positive for Ebola, marking the country's first confirmed case linked to the current outbreak, the health ministry said on Wednesday.

The patient has been placed in isolation and health authorities are tracing contacts, the ministry said in a statement, adding that the risk to the wider European population was low.

Congo's Ebola outbreak is linked to the rare Bundibugyo strain of the virus. It has infected more than 1 000 people and killed 267 — generating the largest number of confirmed cases within the first month of any episode of the disease, the World Health Organisation said this week.

Experts say the disease was probably circulating for months before it was officially declared on May 15. Early confirmed cases were identified in urban areas, and infections have since been reported in at least three densely populated displacement camps.

The two largest previous Ebola outbreaks occurred in West Africa — in Guinea, Sierra Leone and Liberia between 2014 and 2016 — and in Congo in 2018.

A US citizen treated for Ebola in Germany was discharged earlier this month after no virus had been detected in the patient since May 30.