A Thai policeman wearing plain clothes has been charged with illegal possession after being discovered trying to smuggle 20 elephant tusks, officials have said.

The policeman was stopped at a checkpoint in the southern province of Chumphon on Saturday where authorities discovered the haul in the police van he was driving.

“We found 10 pairs of elephant tusks in the van and charged him with illegal possession of elephant tusks, which he confessed to during the investigation,” Police Colonel Chalard Polnakarn told AFP.

The origin of the tusks remains unclear.

Illegal trade in elephant ivory, especially elephant tusks from Africa, has increased over the years, fueled by demand in Asia and the Middle East. According to conservationists, hundreds of tonnes of ivory from Africa is smuggled into Thailand every year and passed off as coming from Thai elephants, which can be legally traded.

The arrest comes as Thailand prepares to host the Convention on International Trade in Endangered Species of Wild Flora and Fauna in Bangkok on March.