A photo posted by APOPO (@herorats) on Jul 11, 2015 at 3:30pm PDT Subscribe | UPI Odd Newsletter Subscribe PHNOM PENH, Cambodia, July 16 (UPI) -- A Belgian nonprofit said land mines in Cambodia are being cleared with help from some unusual experts -- "Hero Rats" trained to sniff out TNT. The nonprofit, APOPO, said the 15 African giant pouched rats in Cambodia to assist the Cambodian Mine Action Center were trained in Tanzania to sniff out TNT and signal their handlers by scratching the ground. Advertisement "We believe the rats will increase the efficiency of our operations," Heng Rattana, director of the Cambodian Mine Action Center, told the Global Post. "We are currently verifying the quality of their work." James Pursey, a spokesman for APOPO, said one rat can search 2,152 square feet in about 20 minutes -- a job that would take a human with a metal detector one to four days to complete. Hulsok Heng, supervisor of the Hero Rat program in Cambodia, said CMAC officials were impressed. "Everybody was awestruck by the rats' size and intelligence. In Cambodia, people don't really look at rats as intelligent, trainable animals. They are treated as a pest, or unhygienic but thanks to the Hero Rats people will change their minds," he said in a post on the APOPO website. Advertisement An estimated 4 to 6 million land mines and other undetonated explosives remain in the fields, forests and riverbeds of Cambodia. More than 64,000 people have been killed or injured by the remnants. Read More Bungee rig takes portable water slide to the next level of speed Small dog refuses to let tall wheat keep him down Illinois fair: Dog-riding monkey races will go on despite protests