At least half the elephants in Cameroon's Bouba N'Djida reserve were slaughtered because the west African nation sent too few security forces to tackle poachers, the World Wide Fund for Nature said on Thursday.

In what was described as one of the worst poaching massacres in decades, as many as 200 elephants have been killed for their tusks since January by poachers on horseback from Chad and Sudan, the fund said.

Rising demand in Asia for jewelry and ornaments made from elephant tusks is understood to be among the factors behind the spike in poaching.

"WWF is disturbed by reports that the poaching continues unabated," Natasha Kofoworola Quist, WWF's representative in the region, said in a statement.

It was the second major elephant-poaching report out of Africa this month. On March 5, the warden at Virunga National Park, a U.N. World Heritage Site in the Democratic Republic of Congo, said poaching had become so severe that rangers began using bloodhounds to track down poachers. The Virunga elephant population has fallen to fewer than 400 from an estimated 3,000 in the 1980s.

In Cameroon, about 20 fresh elephant carcasses were discovered last week, a WWF spokesperson said.

The government of the Central African state has sent special forces to track the poachers and end the killing spree in the north of the country, but the WWF said this may be too little, too late.

"The forces arrived too late to save most of the park's elephants and were too few to deter the poachers," Quist said. She said the organization regretted that a soldier was killed during a clash with the poachers.