The disclosure that taxpayers' money was used to cover the companies' compliance costs raises new questions over the relationship between Silicon Valley and the NSA. Since the existence of the program was first revealed by the Guardian and the Washington Post on June 6, the companies have repeatedly denied all knowledge of it and insisted they only hand over user data in response to specific legal requests from the authorities.

The Bloomberg news agency reported that anonymous US officials had said there had been "a few cases" where NSA officials or contractors had used agency surveillance tools or data to spy on people in which they had romantic interests.

According to one of the documents, NSA experts succeeded in getting into the UN video conferencing system and cracking its coding in 2012.

The document said: "The data traffic gives us internal video teleconferences of the United Nations (yay!)."

If I had my way Snowden would get his own statue.