A small team of US Marines are to head soon to Chad's Zakouma National Park to train local forces in the fight against the poaching threatening the area's elephant herds.

Around 15 marines are to arrive in the Central African country by the end of April and will stay for around a month, a military official said.

The troops will train a group of approximately 100 rangers from the Chadian environment ministry's mobile brigade tasked with tracking poachers.

The marines will train the Chadian rangers on small unit tactics and patrolling, shooting and navigation.

"These skills will help prevent poaching, investigate incidents and pursue criminals," the Marine Corps said in a statement.

An increase in poaching in Zakouma has led to a sharp decline in the elephant population -- from 4,000 in 2005 to 450 just five years later -- according to the African Parks conservation group.

In February, authorities incinerated a ton of ivory confiscated from poachers in the park.

The price of a kilogram of ivory has surpassed $2,000 on the Asian black market, with demand constantly rising, according to several conservation groups.

Central African countries are exploited by vast poaching operations organized by armed groups which take advantage of gaps in border security, allowing illicit goods to pass from country to country.

According to a 2013 report from the World Wildlife Fund, at about $19 billion a year, poaching has become the world's fourth largest illegal market, after drugs, fake currency and human trafficking.

The marines sent to Chad will come from a special unit assigned to the NATO base in Signoella, Italy. The Special-Purpose Marine Air-Ground Task Force conducts cooperation missions in Africa.