Police suspect the gold biscuits were brought from foreign countries, including Switzerland, as they have specific markings on them.
The incident occurred last night when crime branch sleuths laid a trap at MIDC Road on a specific input and detained four persons on suspicion. Police also found three more persons sitting in a car parked in a nearby building and detained them as well.
During search of the car, police found 10 gold biscuits, weighing 100 grams each which were kept in a sweets box, and eight biscuits of one kg each - totalling 9 kgs, a senior official said.
Another official said the gold biscuits were meant to be sold to some persons in the exchange of their old notes in denominations of Rs 500 and Rs 1000 at a premium. Police are trying to find out who were the intended customers.
Joint Commissioner of Police (Crime) Sanjay Saxena said, "Crime branch has sent letters to Income Tax and Customs departments for further investigation.