A spokesperson from the FO told Express.co.uk on Friday: "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".
In a statement, Mr Johnson said: "I am delighted to announce that two British nationals who were held hostage in the Democratic Republic of Congo have been released".
The Britons were released unharmed, while the driver was injured, the British government said.
Boris Johnson did not supply any additional particulars within the assertion launched Sunday, however paid tribute to the authorities from the African nation and the Congolese Institute for Nature Conservation "for his or her tireless assist throughout this awful case".
A park ranger killed by the kidnappers has been named as Rachel Masika Baraka.
Because rebel groups still control large portions of the territory, the Foreign Office advises against all but essential travel to the cities of Goma.
The pair, whose release was arranged by guards at Virunga National Park, are uninjured and no ransom was paid, ITV News Africa Correspondent John Ray said.
Located in Congo's North Kivu province, the park is one of the most important conservation sites in the world, covering 7,800 square kilometres (3,011 miles) - three times the size of Luxembourg.
Congolese authorities are working with the Foreign Office to repatriate the British tourists, according to a park statement. The UNESCO World Heritage is home to around a quarter of the world's remaining mountain gorillas, and contains more mammals, reptile and bird species than any protected area on the African continent.
Park director Emmanuel de Merode said: "Ranger Baraka's life was tragically cut short in service to Virunga National Park".
On April 9, five rangers and a driver were killed in an ambush in the park.
The Foreign Office now - and before the kidnapping - advises against travelling to the area.