Google security experts have said that 21 out of the world’s top 25 news outlets have been the target of ‘state-sponsored’ hacking attacks.

Shane Huntley, one of the software engineers at Google, said journalists and the media were "massively over-represented" in targeted attacks launched by hackers.

The paper was presented on Friday in Singapore at the annual Black Hat hackers conference.

Speaking to Reuters, Huntley said: "If you’re a journalist or a journalistic organisation we will see state-sponsored targeting and we see it happening regardless of region, we see it from all over the world both from where the targets are and where the targets are from."

Reuters reported that the researchers did not want to go into further detail about how Google knows about the attacks.

Forbes, the Financial Times and even the New York Times have all been attacked by hackers in the past 12 months, and the researchers also admitted that Chinese hackers have penetrated a ‘major’ Western news organisation, but declined to identify which one.

Morgan Marquis-Boire, the other Google researcher, said that the number of attacks on journalists was much higher than originally made public.

He told Reuters: "This is the tip of the iceberg."

He also noted the icreased trend amongst journalists for increased data privacy, with higher usage of encrypted email services and Tor.

"We’re seeing a definite upswing of individual journalists who recognise this is important."