A man walks by the poster for the film "The Interview" outside the Alamo Drafthouse theater in Littleton, Colorado December 23, 2014. [Photo/Agencies]

The US State Department on Monday basically rejected a US Senator's claim that China knew about or was involved in the cyberattack against Sony Pictures.

US State Department spokesman Jeff Rathke said in a daily press briefing that the US government stands behind an FBI report which held the Democratic People's Republic of Korea solely responsible for the hacking of Sony Pictures.

"I can't imagine anything this massive happening in North Korea without China being involved or at least knowing about it," Senator Lindsey Graham, a Republican from South Carolina, told CNN's Dana Bash on "State of the Union" on Sunday. Graham called for additional US action against the regime to make it "feel the pain that is due".

Jonathan Pollack, senior fellow at the John L. Thornton China Center of the Washington-based Brookings Institution, said Graham was making a serious charge without any evidence.

"I have no idea why Senator (Lindsay) Graham would suggest that China was somehow involved in the cyberattack on Sony Pictures," Pollack told China Daily. "He is making a serious charge without offering any evidence at all to substantiate his claim. It's more what he believes rather than what he knows. His remarks are decidedly unhelpful in addressing the cyber threat increasingly prevalent in the corporate world."