The bills in old denominations of Rs 500 and Rs 1000 were seized when they were being taken for exchange with new currencies, ostensibly for a commission.
"We got a tip-off that the fake scrapped currency was being carried in a taxi for exchange last night," the DCP (Zone VII) Sachin Patil told reporters at a press conference.
The vehicle was intercepted at LBS Marg Road in Ghatkopar after a brief chase, the officer said.
The police found two bags placed on rear seats of the cab, containing Rs 1,51,78,500 in old notes.
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"Police are probing whether any NRIs were involved in the matter as the deadline for exchange of invalid notes by residents who were abroad during the cash ban is ending tomorrow," the officer said.
The accused have been identified as Rizwan Qazi, the driver of the car who had fetched the money from Gorai, Rehman Sheikh, Danish Rafi and Aiyaz Akthar.
Police suspect that Sheikh, Rafi and Akhtar are middlemen, who had boarded the taxi near Mumbai Dockyard.