"The Polit Bureau of the CPI(M) demands that the Manmohan Singh Government immediately lodge a strong protest against the US snooping activities and demand its halt forthwith," the party said.
In a statement, the Left party said the UPA government should have strongly protested against such surveillance and bugging but alleged that External Affairs Minister Salman Khurshid has sought to justify American actions.
"It is not snooping. It is only computer study and computer analysis of patterns of calls," the party quoted Khurshid as saying.
Reports claiming that the US National Security Agency has been bugging the Indian embassy in Washington along with the embassies of 37 other countries come after an earlier revelation that the US has been mining internet and telephone data from India on a large scale, it said.
"India has a foreign minister who is not worried that the Indian embassy in Washington is bugged by the US intelligence agency.
"This shameful remark has come at a time when even the close allies of the United States like Germany and France have protested against the US snooping on their countries," the statement said.