"Six members of the defence forces and two civilian guides were killed " on Thursday during a clash with heavily-armed men on horseback in Bouba Ndjida national park in the north of the country, Beti Assomo said in a statement aired on state radio.

In 2012, 128 elephants were killed in the Bouba Ndjida park within two months, according to the government. The Worldwide Fund for Nature (WWF) put the figure at 480.

The WWF attributed that massacre to poachers from Sudan and Chad.

Since March 2012, Cameroon has deployed a hundred troops in the wildlife reserve to help deal with the threat from poachers and protect the elephant population for which the park is known.

The eight people killed in Thursday's violence were carrying out a routine patrol, source said.

Poaching has killed an estimated 110,000 elephants over the last decade, with transnational organised crime syndicates taking over the illicit trade.

The most recent figures, for 2016, showed the global trade in illegal ivory continues to thrive in light of record seizures despite a decline in poaching.

According to the Great Elephant Census in 2016, the first ever pan-African survey of savanna elephants, numbers are estimated to have fallen to 352,000, down from 1.3 million in 1979.