South Korea has blocked access to the official North Korean Twitter account, a few days after the latter started posting messages on the microblogging service.

The Twitter feed @uriminzok was launched last week and has been providing Korean-language headlines and links to propaganda-heavy news items on its page.

South Korea's Communication Standards Commission concluded that the tweets are illegal under the decades-old National Security Law, because they "praise, encourage sympathy for, publicise, or support the North Korean regime's activities."

Han Myung-ho, a commission official, said that they decided to act immediately, after having considered the unique nature of social networking services like Twitter, "where specific information can be dispersed to thousands in a short period of time".

The commission has so far restricted access to 65 sites that are pro-North Korea in nature or are run by North Korea.

In 32 tweets, North Korea has denounced its southern counterpart, describing reports that North Korea sank a South Korean navy ship as a "conspiracy".