DHAKA, Bangladesh (Reuters) -- Bangladeshi police said on Monday they had captured two monkeys trained to deliver drugs to addicts in the capital Dhaka.

The monkeys were captured on Sunday in Dhaka's Sabujbagh area and placed in the zoo after an anonymous caller said drug dealers had been using the monkeys to carry drugs to buyers and collect their money, a policeman said.He said the monkeys -- named Munni and Hamid -- were trained to perform the unique job, and police were investigating to see if other drug dealers were also using monkeys.

"Using monkeys in the illegal trade has been detected for the first time, and we are exploring if there are more such cases," police officer Liaquat Hossain said.

Police said they could not arrest the drug sellers yet but had seized a huge quantity of bottled phensidyl, a syrupy liquid that contains codeine.