Democratic Republic of Congo’s Virunga National Park, closed last month after the ambush of a tourist group that left a ranger dead, said it would not reopen until next year.
Britons Robert Jesty and Bethan Davies and their Congolese driver were kidnapped three weeks ago by gunmen in the east of the park and released three days later.
Park ranger Rachel Makissa Baraka (25) was killed trying to defend them.
The park’s communications unit said tourist activities, initially suspended until June 4 to investigate the incident, would not resume until next year.
“It is abundantly clear the Virunga region is deeply affected by insecurity,” Chief Warden Emmanuel Merode wrote in a letter to the park’s partners and clients.
“Much more robust measures are needed than in the past and this will require a significant investment.”
Warfare in eastern Congo between 1996 and 2003 killed millions of people, mainly through hunger and disease.
Virunga sits on the forest-cloaked volcanoes of central Africa and is home to over half the global population of mountain gorillas.
It is Africa’s oldest national park and largest tropical rainforest reserve, covering 7,800 sq km. Since tourism was relaunched in 2014 it has had more than 17,000 visitors.
Armed militia still control large swathes of territory in and around it and more than 175 rangers died protecting the park.
Last week, wildlife authorities said the population of mountain gorillas had risen to 604, up from 480 in 2010.
There are currently 1,004 individuals of the critically endangered gorilla sub-species in the world – a more than 25% increase on 2010.