Two British nationals who were held hostage in the Democratic Republic of Congo (DRC) have been released, British Foreign Secretary Boris Johnson said on Sunday.

"I am delighted to announce that two British nationals who were held hostage in the Democratic Republic of Congo (DRC) have been released," Johnson said in a statement.

"I paid tribute to the DRC authorities and the Congolese Institute for Nature Conservation for their tireless help during this terrible case," said the statement.

The two British tourists were kidnapped last week at a national park which is well known for its rare mountain gorillas in the central African country.

"My thoughts are now with the family of Virunga Park ranger Rachel Makissa Baraka who was killed during the kidnapping, and with the injured driver," Johnson said in the statement.

The two tourists, together with their driver, were abducted in Virunga National Park in the DRC. The kidnapping took place near the village of Kibati, which is located just north of Goma -- the capital city of eastern DRC's troubled North Kivu province, one of the most volatile parts of the country.

The female park ranger was killed trying to protect the two British tourists after gunmen ambushed their vehicle in the national park.

The woman, named locally as Rachel Katumwa, was gunned down as the two Britons were dragged away and marched through the forest by their attackers.

The driver, Guystave Mbiye, who was wounded during the attack, was last night recovering in hospital after being freed by the gang.

The Virunga National Park is home to between a quarter and a third of the world's highly endangered Mountain Gorilla, but it is also the hideout of a dozen militias and rebel outfits from three different countries, remnants of DRC's civil war, as well as bands of poachers and criminal gangs.

Together they have made the park the most dangerous in the world for rangers and conservationists to work in, with some 170 wildlife rangers killed there in the past 20 years, including five who were murdered along with their driver after an ambush last month.

Although a number of Congolese nationals have been abducted in the park in recent years, it is the first time in nearly 20 years that an attempt has been made to seize Western tourists, reports quoted local DRC officials as saying.