A number of North Korean websites and networks targeted by an international hacking group are offline, sources said Tuesday.

Internet monitors said the websites of the Korean Central News Agency, the Rodong Sinmun and portal Naenara were all out of service as of 11 a.m.

The sites were all targeted in advance by the Anonymous Group, which said it would launch attacks to mark the 63rd anniversary of the outbreak of the 1950-53 Korean War.

The loosely associated hacktivist group, whose members have never been identified, claimed it planned to attack the networks because the North, in defiance of warnings from the international community, launched a long-range rocket, tested a nuclear device in February and threatened to start a new war on the Korean Peninsula.

Anonymous broke into Uriminzokkiri, the North's main Internet-based media and propaganda website in April. It also defaced Minjok Tongshin, an English language news provider, Paekdu-Hanna.com, Jajusasang.com and Ryugyong Clip, a video and still image site. (Yonhap News)