In a letter to Prime Minister Manmohan Singh, he also urged him to raise the issue with US President Barack Obama why such activities were being carried out, if such reports were correct.
Maintaining that he had raised the issue in the last Parliament session and alleging that the government had not taken note of it, Dasgupta said the latest report "is more outrageous. It is saying that boundless informant was used for monitoring telephone calls and making access to Internet in India. It has nothing related to terrorism".
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"If the report is true, which you can only clarify, then Indian sovereignty is shamefully undermined, Indian security is despicably jeopardised, privacy of the citizens is surely outraged," the CPI leader said, adding that access was being acquired through the servers of Google, Microsoft and others.
"I implore upon you to find out from the American government particularly from President Obama why it is being done... I hope the government of India will find out enough justification to enlighten the nation if the news as appeared is right or wrong, true or false," Dasgupta said.
The report quoted a secret document disclosed by whistleblower Edward Snowden that the NSA's PRISM programme was deployed to gather key information from India by tapping directly into the servers of tech giants which provide services like email, video sharing, voice-over-IPs, online chats, file transfer and social networking services.