JOHANNESBURG (AP) — South Africa says an illegal shipment of lion bones weighing 342 kilograms (754 pounds) has been seized at Johannesburg’s main airport.

An environment ministry statement says the bones were found wrapped in tin foil inside a dozen wooden crates. The ministry says three people have been arrested after the discovery on Tuesday.

It is not immediately clear where the lion bones were being shipped. The statement says the cargo had been misdeclared.

South African policy allows the annual export of a certain number of skeletons of captive-bred lions to meet demand in Asia for bones, but some animal rights groups have objected.

Conservationists say the enforcement of regulations governing the lion bone trade is weak and that the legal market could threaten Africa's wild lions by spurring demand.