The US National Security Agency has bugged the United Nations’ New York headquarters, Germany’s Der Spiegel weekly said yesterday in a report on US spying that could further strain relations between Washington and its allies.

Citing secret US documents obtained by fugitive former intelligence contractor Edward Snowden, Der Spiegel said the files showed how the US systematically spied on other states and institutions.

Der Spiegel said the European Union and the UN’s Vienna-based nuclear watchdog, the International Atomic Energy Agency, were among those targeted by US intelligence agents.

In the summer of 2012, NSA experts succeeded in getting into the UN video conferencing system and cracking its coding system, according one of the documents cited by Der Spiegel.

Surveillance is intensive and has little to do with terrorism

“The data traffic gives us internal video teleconferences of the United Nations (yay!),” Der Spiegel quoted one document as saying, adding that within three weeks the number of decoded communications rose to 458 from 12.

Internal files also show the NSA spied on the EU legation in New York after it moved to new rooms in the autumn of 2012.

Among the documents copied by Snowden from NSA computers are plans of the EU mission, its IT infrastructure and servers.

According to the documents, the NSA runs a bugging programme in more than 80 embassies and consulates around the world called “Special Collection Service”.

“The surveillance is intensive and well organised and has little or nothing to do with warding off terrorists,” wrote Der Spiegel.

Snowden’s leaks have embarrassed the US by exposing the global extent of its surveillance programmes.

Washington has said its spies operate within the law and that the leaks have damaged national security.

Earlier this month, US President Barack Obama announced plans to limit US government surveillance programmes, saying the US could and should be more transparent.