India has condemned US spying on the country’s ruling party as “unacceptable” after recent allegations that Washington’s National Security Agency (NSA) targeted the newly-elected Bharatiya Janata Party (BJP).

“I raised this issue (US spying) and ... when the news came out in the Indian media, people were angry,” Foreign Minister Sushma Swaraj said at a joint press conference with her visiting counterpart John Kerry in the capital, New Delhi, on Thursday.

Last month, American newspaper the Washington Post made public a classified document, supplied by fugitive former NSA contractor Edward Snowden, which showed that the BJP was among the targets for the NSA in 2010 while it was India's main opposition.

India summoned the top diplomat at the US embassy in New Delhi, in response, to protest.

India also complained to the US on two other occasions in 2013 over other surveillance revelations, including the disclosure that its UN mission in New York and its Washington embassy were under surveillance.

Kerry told reporters that he could not comment on the issue. “We have a policy in the United States with respect to intelligence matters, we do not discuss intelligence matters in public.”

Last year, Snowden leaked two top secret US government spying programs under which the NSA and the Federal Bureau of Investigation (FBI) have been eavesdropping on millions of American and European phone records and the Internet data from major Internet companies such as Facebook, Yahoo, Google, Apple, and Microsoft.

SS