The research was conducted in South Africa involving the U.S. military.
On a game reserve co-owned by Sean Hensman, three elephants passed the smell tests.
Sniffing at buckets, they were rewarded with a treat of marula - a tasty fruit - when they showed that they recognized samples of TNT by raising a front leg.
Stephen Lee, head scientist at the US Army Research Office, which backed the study financially, said that elephants remember their training longer than dogs.
The elephants detected TNT samples 73 out of the 74 times that they encountered in a line of buckets, according to Ashadee Kay Miller, a zoology student at the University of the Witwatersrand in Johannesburg.
They only got this wrong 3.6 per cent of the time over 502 buckets that contained the explosive, which was dissolved in acetone on filter paper.
All other buckets were filled with acetone and filter paper only.
In a second set of tests, the elephants scored 100 percent, detecting TNT in 23 out of 23 buckets when 'distractor odours' such as tea, bleach, soap and gasoline were placed in the other buckets.
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