Cambodian customs Friday seized more than 600 kilograms of illegal ivory in a container packed with corn that had languished unclaimed at a port for two years after being shipped from Africa.

The haul was made after officials decided to open the container, which had been left at the southwestern port of Sihanoukville weeks after a crackdown on ivory smuggling in 2014.

"The shipment arrived at the port more than two years ago... but nobody has come to claim it," Kin Ly, head of the port's customs office.

"The elephant tusks were hidden underneath sacks of corn," Kin Ly said, adding that the ivory had been shipped from Africa and was destined for a third country.

He was unable to say which country or provide an estimate of how much the tusks worth.

In 2014, Cambodia seized more than three tonnes of ivory -- the country's largest-ever haul of elephant tusks -- hidden in a container of beans.

The same year, Cambodian police arrested two Vietnamese men who were trying to smuggle nearly 80 kilograms (180 lbs) of illegal ivory from Africa.

Kin Ly said the container may not have been claimed because of links with those smuggling groups. 

Conservationists have voiced concern that Cambodia is emerging as a key transit route for African ivory, which often makes its way to wealthy buyers in Vietnam or China.

Poaching of elephants has risen sharply in Africa to meet demand in Asia.

More than 35,000 elephants are slaughtered each year on the African continent from an approximate population of more than 450,000 in the wild.