Reports that two Britons have been kidnapped in the Democratic Republic of Congo are being investigated by the Foreign Office.
Local media say a female wildlife ranger – who was with the pair – was killed.
The incident took place just north of the city of Goma in the Virunga National Park in North Kivu province.
The area, known for its mountain gorillas, has seen a number of killings and kidnappings in recent years.
A Foreign Office spokesman said: “We are in close contact with the authorities in Democratic Republic of the Congo following an incident involving two British nationals, and our staff are providing support to their families.”
The national park, which runs along the border with Uganda and Rwanda, covers 3,000 sq miles (7,800 sq km).
Armed groups are fighting for control of territorial and natural resources in the area.
Five rangers and a driver were killed on 9 April.
The Foreign and Commonwealth Office advises against all but essential travel to Goma and urged Britons not to travel beyond the city.
The advice, which was last updated two days ago, said tourists are vulnerable if travelling without escorted transport in the eastern part of the country and the “risk of kidnap or injury as a result of armed or criminal activity remains high.”
It added that British government staff are not always in the area and the British embassy’s ability to offer consular assistance may be “severely limited”.
In April, the director of Virunga National Park, Emmanuel de Merode, told the BBC World Service that recent attacks were part of “a bigger picture which involves the trafficking of natural resources”.
He said the park is protected by around 800 rangers but there are also estimated to be between 1,500 and 2,000 militia in and around the park.
The park is a Unesco world heritage site and is home to critically-endangered mountain gorillas as well as lions, elephants and hippos.