Kenyan authorities have seized 300kg (660 lbs) of illegal ivory hidden in coffins on a plane bound for Laos.
The haul included 16 elephant tusks and black rhinoceros horns. Officials said the blood on the ivory suggested the animals had been killed very recently.
The flight - which stopped in Nairobi - originated in Mozambique and was bound for Thailand and then Laos.
The haul of ivory may have had a value of about $1m (£614,000), Reuters reports.
Officials from Kenya's Wildlife Service said the ivory might have come from Tanzania or South Africa.
The black rhino is found only in eastern and southern Africa.
The international ivory trade has been banned since 1989. The sale of ivory is illegal if the ivory is not from pre-1989 stockpiles.
However, some countries have done little to enforce the ban.