NAIROBI, Kenya (AP) — Wildlife officers seized two tons of elephant ivory and five rhino horns at Kenya's main airport that were to be illegally shipped to Malaysia, an official said Tuesday.

Paul Udoto, a spokesman with the Kenya wildlife Service, said sniffer dogs from the KWS inspection unit, based at the Jomo Kenyatta International Airport, detected the tusks. They were concealed in wooden boxes being transported with avocados and destined for Malaysia.

Two people have been arrested, he said.

Udoto said the 317 pieces of elephant tusk are believed to have been acquired after the deaths of 150 elephant. He estimated that it took 20 years to amass the collection and said it is unlikely the elephants were killed for the tusks but rather that someone collected them from elephants that died naturally.

Udoto said three of Rhino horn had transmitters in them, meaning they were being tracked by wildlife officials.

Airports in Kenya, Ethiopia and South Africa have emerged as the three main airports to smuggle African ivory to Asia, where it is a collector's item.

Early last month authorities in Thailand netted 1,683 pounds (765 kilograms) that were flown from Kenya. In May, Vietnamese authorities discovered nearly two tons of elephant tusks illegally imported from Kenya hidden in dried seaweed. The shipment was bound for China.

According to wildlife officials, elephant poaching has risen seven-fold in Kenya since a one-time ivory sale was approved in 2007 by CITES — the Convention on International Trade in Endangered Species — for four African countries. Last year 271 Kenyan elephants were killed by poachers, compared with 37 in 2007.

CITES banned the sale of ivory in 1989 after poaching devastated the African elephant population from 1.3 million in 1979 to about 600,000 in 1989.