DAKAR, Senegal - Renewed fighting Saturday inside a national park in Congo that is home to endangered mountain gorillas forced rangers to flee for the second time in less than a week, conservationists said.

The clashes between fighters loyal to warlord Laurent Nkunda and government soldiers took place in Virunga National Park, where some of the world's last remaining mountain gorillas live on the slopes of a volcanic mountain range that straddles Congo's border with Rwanda and Uganda, the international conservation group WildlifeDirect said.

Tens of thousands of people have been displaced by the fighting across North Kivu province, where the park is located, and tens of thousands more have fled into neighboring Uganda.

About 300 people _ rangers and their families _ fled the park itself on Monday after skirmishes first broke out there. Wildlife groups said huge swaths of the park, including several of the rangers' patrol posts, had been occupied by Nkunda's insurgents and looted.

Concerned about the fate of the gorillas, a few rangers returned Friday. In the brief time they were there they found only one five-member group outside of the park and "vulnerable to crossfire," WildlifeDirect said. The rangers reported hearing shelling and gunfire on Friday and Saturday, and fled again before they were able to check on any other gorillas.

Though they typically stay high up on the mountain slopes, the gorillas can roam freely and the park is not fenced off.

"We thought the situation was calming a couple of days ago, but once again the mountain gorillas are in peril and the rangers cannot do their job," the director of WildlifeDirect, Dr. Emmanuel de Merode, said in a statement. Conservation is "consistently challenging, and we can only hope the mountain gorillas survive this most recent saga."

Only about 700 mountain gorillas remain in the world, an estimated 380 of them in the Virunga range. About 100 of those are believed to live on the Congo side of the border, where nine gorillas have been killed since January. The other 320 live in Uganda's Bwindi Impenetrable Forest.

"It is imperative that we get into the sector to check on the mountain gorillas. They have been exposed for nearly a week to fighting," said Norbert Mushenzi, director of the southern sector of the park for the Congolese Institute for the Conservation of Nature.

One park ranger was shot and killed late last month in a separate patrol post attack at Virunga, officials said. More than 150 rangers have been killed in the past decade at five national parks in eastern Congo while protecting wildlife from poachers, rebels and illegal miners.

Other game reserves in the area have faced similar threats, including Kahuzi-Biega National Park farther south, which is home to endangered eastern lowland gorillas.

Virunga National Park is located in a lawless swath of eastern Congo that the country's government has struggled to bring under control for years. Established in 1925 as Africa's first national park, it was classified as a U.N. World Heritage Site in 1979.

Congo is still coping with the effects of a 1998-2002 war that drew in the armies of more than half a dozen African nations. Nkunda's fighters, believed to have close ties to neighboring Rwanda, first rose up against the government after the broader war ended five years ago.

In neighboring Tanzania on Saturday, Congo's President Joseph Kabila and his Ugandan counterpart, Yoweri Museveni, signed an agreement to immediately pull back their troops 93 miles from the border to ease tensions over an oil-rich border lake north of Virunga.

Several cross-border skirmishes last month in the Lake Albert area left at least four people dead _ three Ugandans and one British oil contractor.

The two leaders agreed to work together to explore and exploit oil in the area and to lay a joint pipeline to distribute any oil.