An orphaned baby mountain gorilla photographed in the Virunga National Park in the Democratic Republic of Congo on September 10, 2016. The Britons and driver were freed two days later.
Kidnappings and murder have forced the famed Virunga wildlife park in the Democratic Republic of Congo to close for visitors until 2019, the authorities said Monday.
Tourist activities in the park had initially been suspended until 4 June while the incident was investigated.
"It is abundantly clear that the Virunga is deeply affected by insecurity and that this will be the case for some time", park director Emmanuel de Merode said in a statement.
"Much more robust measures are needed than in the past, [and] this will require a very significant investment".
In recent months, the DRC has appeared close to plunging back into the appalling violence of the 1997 to 2003 civil war, in which around five million people died.
Virunga sits on the forest-cloaked volcanoes of central Africa and is home to over half the global population of mountain gorillas.
Virunga park managers say they have received more than 17 000 visitors since relaunching tourism in 2014, and that the industry is key to supporting local communities.
But armed militia still control large swathes of territory in and around it, and more than 175 rangers have been killed protecting the park.
Founded in 1925, the 3,000 sq. mi. nature reserve is renowned for its population of endangered mountain gorillas.
There are now 1,004 individuals of the critically endangered gorilla sub-species in the world - a more than 25 percent increase on 2010.