U.S. President Barack Obama is chiding China over alleged state-sponsored cyber attacks on America.  China denies the allegations and says it is the target of such attacks.

President Obama says "What is absolutely true is that we have seen a steady ramping up of cyber security threats. Some are state sponsored. Some are just sponsored by criminals.

"We've made it very clear to China and some other state actors that, you know, we expect them to follow international norms and abide by international rules.

"And we'll have some pretty tough talk with them. We already have."

It comes after U.S. security officials said cyber attacks had replaced terrorism as the main security threat.