MOSCOW (Reuters) - Russian state media company VGTRK has been targeted in an unprecedented cyberattack, Kremlin spokesman Dmitry Peskov said on Monday, saying that specialists were working hard to determine who was responsible.

VGTRK, which owns and operates Russia's main national TV channels and a slew of regional channels and radio stations, said earlier on Monday in a statement that its online service had come under cyberattack overnight, but that radio and TV broadcasting were working as normal despite the attack.

"Our state media holding, one of the largest, has faced an unprecedented hacker attack on its digital infrastructure," Peskov told reporters, saying VGTRK was working to overcome the consequences of the attack.

"Specialists are working to find out all the circumstances, to understand where the traces left behind by those who organised this hacker attack on the critical infrastructure object lead."

VGTRK, the All-Russia State Television and Radio Broadcasting Company, did not immediately respond to a Reuters request for comment.

(Reporting by Dmitry Antonov; Editing by Andrew Osborn)