Congolese soldiers and park rangers have launched an operation to locate two British tourists kidnapped in the country's volatile eastern borderlands, an army spokesman said.
Robert Jesty and Bethan Davies were abducted along with their driver on Friday while visiting Africa's oldest national park. "That would put their lives in danger".
Two British tourists have been released unharmed by the captors in the Democratic Republic of Congo, Foreign Secretary Boris Johnson announced Sunday.
Founded in 1925, the Viruga National Park is a Unesco heritage site and one of the most important conservation sites in the world. The park covers 300 square miles.
It is home to to around a quarter of the world's critically endangered mountain gorillas and other endangered species as well as lions, elephants, hippos and a host of rare bird species.
Because rebel groups still control large portions of the territory, the Foreign Office advises against all but essential travel to the cities of Goma.More news: Lewis Hamilton ends Sebastian Vettel's pole run at Spainish Grand Prix
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A fifth of the park's southern sector was deforested owing to illegal charcoal production, the park said.
Although a number of Congolese nationals have been abducted in the park in recent years, it is the first time in almost 20 years that an attempt has been made to seize Western tourists, reports quoted local DRC officials as saying.
Virunga has experienced waves of violence and crime linked to local unrest. Park officials blamed Mai Mai militia members.
A female ranger travelling with them was killed and their driver was also taken captive, a park spokesman said.
Together they have made the park the most risky 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.
On April 2, a park ranger died in an attack by armed men while guarding the site of a hydroelectric plant that is under construction.