Prime Minister David Cameron has been warned about “the perceived slide in press freedom witnessed in the UK over recent months” and has been called on to reaffirm the Government’s “commitment to a free and independent press”.

The warning from the World Association of Newspapers and News Publishers (WAN-IFRA) came in response to last week’s revelation that The Guardian, under supervision of UK security services, destroyed material relating to National Security Agency whistleblower Edward Snowden.

The body, which claims to represent 18,000 publications in more than 120 countries, said it had “deep concern” at the supervised destruction of the NSA files, which it described as “an act of intimidation”.