GOMA, Congo (Reuters) - Park rangers returned to a reserve that is home to nearly a third of the world’s remaining mountain gorillas Friday, more than a year after fighting forced them to abandon the area, a park chief said.

Mountain gorillas from the Kabirizi family rest in Virunga National Park in this handout photo released by the WildlifeDirect on September 4, 2007. REUTERS/WildlifeDirect/Handout

Armed Tutsi rebels loyal to renegade General Laurent Nkunda occupied the gorilla sector of Virunga National Park in September 2007, forcing rangers to leave.

An offensive by Nkunda’s rebels forced the rangers to abandon the rest of the park, Africa’s oldest, late last month when the Rumangabo park headquarters, from which conservation operations were run, fell to a rebel assault.

Nkunda’s offensive against the North Kivu provincial capital Goma and other towns in North Kivu province has displaced around 250,000 people, bringing to more than 1 million the number of people displaced by two years of conflict in North Kivu.

“It is a huge step that all sides have agreed that the protection of Virunga as a World Heritage Site and its mountain gorillas is of sufficient priority to transcend political differences,” park Director Emmanuel de Merode said in a statement.

After meeting U.N. envoy Olusegun Obasanjo, a former Nigerian president, Nkunda pulled his fighters back from some positions seized during the past few weeks.

The U.N. Security Council agreed Thursday to send 3,000 reinforcements to the Congo peacekeeping force, the world’s biggest at 17,000-strong.

“Rangers are neutral in this conflict, and it is right that they should be allowed to do their job,” de Merode said.

MOUNTAIN GORILLAS

Virunga’s gorilla sector is home to 200 of the last remaining 700 mountain gorillas in the world, who live in forested hills on the border with Uganda and Rwanda.

“The re-establishment of a Ranger presence in Virunga National Park is paramount to the protection of the flora and fauna in the park,” park authorities said in the statement.

“The rangers are now planning to initiate a census of the habituated mountain gorillas in coming days; the last census in August 2007 indicated there are 72 habituated gorillas, but this figure is expected to have changed due to births, death, and interactions,” it said.

Some of the rangers forced to flee Virunga ended up squatting in squalid refugee camps while they waited to return to their posts.

More than 150 rangers have been killed in eastern Congo in a decade of conflict that has claimed more than 5 million lives -- more than any conflict since World War Two -- through violence, hunger and disease.

Congo’s five-year regional war officially ended in 2003, but various armed factions have continued to fight in the east, often competing for valuable resources such as gold and tin mines and timber.

Park authorities say gorillas and other animals such as elephants, hippos and antelopes are vulnerable to the armed groups who roam the hills and forests of eastern Congo, often using National Parks to camp or move around unseen.

The animals also face threats from poachers, squatters and charcoal burners who destroy their forest habitat.

Virunga’s Gorilla Sector suffered repeated attacks in 2007 during which 10 mountain gorillas were killed.