The official Angry Birds website was defaced by hackers following a leaked National Security Agency document that claimed US and British spy agencies gain access to personal data from the mobile app.
Users trying to access the website late on Tuesday evening were met with an image of one of the Angry Bird characters with an NSA logo and the text "Spying Birds".
Rovia, the video game developer which created the game, denied collaborating with government agencies and sharing data.
"Rovio Entertainment Ltd, which is headquartered in Finland, does not share data, collaborate or collude with any government spy agencies such as NSA or GCHQ anywhere in the world," the firm said in a statement.
“Our fans’ trust is the most important thing for us and we take privacy extremely seriously," said Mikael Hed, CEO of Rovio Entertainment.
"As the alleged surveillance might be happening through third party advertising networks, the most important conversation to be had is how to ensure user privacy is protected," he said.
The Syrian Electronic Army (SEA), known for hacking the New York Times last year, claims an associated group was responsible for the hack.
"A friend hacked and defaced @Angrybirds website after reports confirms its spying on people. The attack was by 'Anti-NSA' Hacker," the SEA tweeted, adding "He sent an email to our official email with the link of the hacked website."