The site said the information was contained in a bank document related to risk observations by the Reserve Bank of India, India's central bank.
According to this document, the data of customers who had accounts with banks that had migrated to Microsoft's Office 365 cloud-based email service was being shared with US intelligence agencies.
It said while customers were unaware of this, the banks in question were fully cognisant of what was going on.
"It was gathered from the Microsoft transparency hub that Microsoft is bound to share customers’ data under US Foreign Intelligence Surveillance Act (FISA) and US national security letters as and when required by the US authorities.”
The RBI document said Microsoft had shared customer data on 3036 occasions following more than 4000 government requests or legal demands.
One bank told the website that it agreed about the data sharing with Microsoft on the proviso that customer data would be shared only if an Indian Government order or a court order was issued.
When Microsoft was asked about this, the company avoided specific questions, but instead gave a response that dealt with its position on privacy.