The US intelligence service National Security Agency (NSA) had bugged the EU embassies in Washington and in New York as well as its offices in Brussels and infiltrated their internal computer networks, a German weekly news magazine has said.
"Documents from September, 2010 classified as 'top secret' by the NSA, which were leaked by former NSA contractor Edward Snowden, revealed how the agency planted bugs at the EU offices in Washington and in New York and gained access to their internal computer networks.
"This enabled the NSA not only to snoop into the conversations at the EU missions, but also to monitor the emails and internal documents on their computers," the news weekly, Der Spiegel, said in its latest edition.
"Five years ago, the NSA also planted bugs and infiltrated the computers and telephone networks at the Justus Lipsius Building in Brussels, headquarters of the EU Council of Ministers and the European Council," according to the report.
Member-nations keep their offices in this building, which is also the venue for high-level ministerial meetings.
EU's counter-espionage officials traced the NSA's infiltration into the building to a closely guarded area used by the American agency's specialists at the NATO headquarters in Brussels, the report said.
An NSA document from September 2010 explicitly named the Europeans as a "location target", Der Spiegel said, adding "the attacks on the EU institutions showed yet another level in the broad scope of NSA's spying activities," the news weekly said.
Documents leaked by whistle-blower Snowden early this month exposed a systematic and large-scale surveillance of phone and internet communications by the NSA around the world.
He had also revealed that the British intelligence service GCHQ operated a similar surveillance programme codenamed "Tempora" under which it monitored and stored internet and telephone data of millions of users by tapping Transatlantic fibre-optic cables and shared those information with the NSA.
Snowden, who fled to Hong Kong before leaking the NSA operations, is believed to be staying at present at a Moscow airport.
Meanwhile, Martin Schulz, the president of the European Parliament, said, "I was deeply shocked and worried about the allegations and warned that if proved true, they would have severe consequences for transatlantic relations."
In an interview, he called upon the US government to fully clarify the allegations and provide speedily all relevant information to the EU authorities.
The Guardian newspaper reported last week that the British surveillance programme was more extensive than that of the NSA.