HARARE, Zimbabwe — Heavy fighting in the Democratic Republic of Congo is threatening the region’s critically endangered mountain gorillas, conservationists said yesterday.

For three months, rangers funded by Wildlife Direct have been unable to enter the gorilla zone in the Virunga National Park in the east of the country because of clashes between 20,000 Congolese soldiers and the 4,000-strong forces of an ex-general, Laurent Nkunda.

The 70 park rangers are among around half a million people who have been displaced in the violence, according to the United Nations.

“In the 34 years I have been a ranger, this is one of the most trying and exasperating moments,” an official with the Congolese Institute for the Conservation of Nature, Norbert Mushenzi, said. “We have been totally unable to do our job due to the senseless fighting.”

The director of Wildlife Direct, Emmanuel de Merode, said that despite their natural shyness, gorillas accustomed to humans were not known to flee the sounds of war. “The situation is absolutely chaotic. There is a war going on around the mountain gorillas. We need the fighting to stop, and we need to know about the welfare of these animals.”

The fighting was triggered by the breakdown of a cease-fire with Mr. Nkunda, who says he is protecting the area’s Tutsi ethnic minority. It is already the worst year on record for gorilla conservation. At least 10 gorillas have been killed, two for bush meat, allegedly by some of Mr. Nkunda’s troops, and charcoal producers have been blamed for eight deaths.