Ugandan officials have seized some two tonnes (4,600lb) of ivory - one of the country's biggest such hauls for many years.
The Uganda Wildlife Association (UWA) has said the 832 pieces of ivory could be worth up to $6.7m but other estimates put the value lower.
Experts say some of the ivory is believed to have come from elephants poached outside Uganda.
There is a huge demand for African ivory in Asia for use in ornaments.
The ivory was apparently heading for the Kenyan port of Mombasa.
Some of the tusks had been broken up and covered with plastic bottles in crates labelled as material to be recycled.
The UWA told the BBC's Catherine Byaruhanga that Uganda is increasingly being used as a transit country by poachers who kill elephants in states such as South Sudan or the Democratic Republic of Congo.
Uganda is believed to have about 5,000 elephants and this haul would represent the tusks from about 400 animals. More....