America's snooping scandal: 10 things to know

A report in UK paper Guardian says India is the fifth most tracked country by the US intelligence agencies. The Indian government has said it will seek details from the US. (Read)

The Guardian claims to have acquired top secret documents about the NSA's data-mining tool, called Boundless Informant. A snapshot of the Boundless Informant data, contained in an NSA "global heat map" allegedly shows that in March 2013 the agency collected 97 billion pieces of intelligence from computer networks worldwide.

The Guardian report said the largest amount of intelligence was gathered from Iran - more than 14 billion reports in that period, followed by 13.5 billion from Pakistan. Jordan, one of America's closest Arab allies, came third with 12.7 billion, Egypt fourth with 7.6 billion and India fifth with 6.3 billion.

Edward Snowden, 29, an American intelligence contractor who worked for the CIA, reportedly claimed responsibility for leaking the NSA's most guarded secrets. He has since fled the US and is believed to be hiding in Hong Kong.

The top secret surveillance program, codenamed PRISM, reportedly gathers hundreds of millions of US phone records to search for possible links to known terrorist targets abroad. It also allows the USA government to tap into nine US Internet companies, including Google, Apple, Facebook and Skype and gather all communications to detect suspicious behaviour that begins overseas.

Google called on the US government on Tuesday, releasing an open letter asking for permission from the US government to provide greater transparency on national security requests, as it sought to distance themselves from reports that portrayed the companies as willing partners in supplying mass user data to security agencies. Microsoft Corp and Facebook Inc soon followed with similarly worded statements in support of Google.

The US government has said this programme is necessary for protecting Americans - and does not trample on their privacy rights. "You cannot have 100% security with 100% privacy. Some sacrifices have to be made," US President Barack Obama said.

The Obama administration has launched an internal review of the potential damage to national security from these leaks.

Senators and technocrats have, meanwhile, pushed the government to be more open about the top-secret programmes. The FBI and intelligence officers were paraded before the US Congrerss as the lawmakers sought answers from the government. The country's main civil liberties organization has sued the government.

The leaks have triggered a fierce debate about Internet privacy. Many inside and outside the US are outraged by the breadth and secrecy of the operation, which was carried out under the broad brush terms of the Foreign Intelligence Surveillance Act (FISA) and the Patriot Act.