Prison officials found the cat on Saturday with a small parcel tied to its neck, entering the Welikada prison in Colombo, the capital.
Prison officials found 1.8 grams of heroin, two SIM cards, and a memory chip used for mobile phones.
“The cat was detained in a room inside the prisons to facilitate investigations, but has escaped from the room,” police said.
However, investigations are proceeding to determine if the cat had been used previously to smuggle drugs and contraband.
Police will check CCTV footage and interview prisoners.
The incident comes shortly after a person attempted to throw a ball packed with heroin into the same prison and was arrested.
It also comes in the wake of tightening security in prisons to prevent smuggling in phones and drugs into prisons.
President Gotabaya Rajapaksa has directed prison officials to strengthen security in prisons after reports that prison inmates were still coordinating criminal activities by mobile phone.
At least three prison officials who helped prisoners by helping them get goods like mobile phones were arrested on Sunday. (dpa/NAN)