Zonal director of Narcotics Control Bureau (NCB) Sunil Sinha said that all related individuals and gangs were under NCB's scanner.
Though most of the drugs were found to have been procured locally, clients are mostly based outside, particularly in the US.
US prime market for Indian online drugs market
Massive seizures made in different cities
Last week, a raid at a Bengaluru call centre led to the seizure of about 5,355 psychotropic substances and prescription drugs in NCB's first such seizure in the city.
A similar racket was busted in Ahmedabad in August 2016 and 10 lakh tablets were recovered.
Later in November, the Department of Revenue Intelligence seized 16 lakh tablets in Mumbai.
US agencies cooperating with Indian counterparts
Sinha said the NCB is analyzing the database recovered from the Bengaluru centre; investigations are still underway, but most clients were found to be located abroad, especially the US.
US agencies are cooperating with Indian authorities to check the menace.
However, a Delhi US embassy spokesperson declined to comment on whether rackets operating in India had been referred by the US to local agencies.
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US Food and Drug Association concerned too
Lyndsay Meyer, US Food and Drug Administration spokesperson, said: "Many websites seem like legitimate pharmacies, leading unsuspecting customers in the US to believe the dispensing pharmacy is in the US or Canada...The majority of counterfeits have been manufactured outside, particularly in China and India."