India has summoned a top US diplomat in New Dehli to complain for the third time about spying, following new claims that the National Security Agency (NSA) targeted Prime Minister Narendra Modi's Bharatiya Janata Party.
"What we have said is that we expect a response and an assurance that this won't happen again," a foreign ministry source told AFP news agency on Wednesday, speaking on condition of anonymity.
Local media also reported strong reactions from the foreign ministry, with one source saying it was "totally unacceptable" that an Indian organisation or Indian individual's privacy was violated.
A new document supplied by fugitive former intelligence worker Edward Snowden and made public by the Washington Post on Monday showed that Modi's BJP was among authorised targets for the NSA in 2010 when it was India's main opposition party.
India has complained to Washington on two other occasions, in July and November 2013, over other revelations, including the disclosure that its UN mission in New York and its Washington embassy were snooped on.
Both times, Washington said it would look into what it can share about its espionage programme but failed to offer any details, the foreign ministry source said.
"We have said that we would like a response, which we haven't received," he said.
The latest incident comes ahead of a planned visit to New Delhi by US Secretary John Kerry, who is expected to meet members of Modi's government in the next few months.
The identity of the US diplomat summoned by the External Affairs Ministry is unclear because the embassy is currently between ambassadors.
Interim ambassador Kathleen Stephens was appointed after former Ambassador Nancy Powell resigned in March.
"As is standard, the US does not comment on its bilateral diplomatic communications with a host government," an embassy spokesman told AFP.