The account opened late Thursday under the Korean username "uriminzokkiri," meaning "on our own as a nation," an official at South Korea's Communications Standards Commission said Friday.
The account opened hours after the commission blocked North Korea's 1-week-old Twitter account from being accessed in the South for containing information that is illegal under South Korean security laws, the official said.
North Korea's government-run website, Uriminzokkiri, announced last week that it has a Twitter account and a YouTube channel created in July.
The Twitter account, under the name uriminzok ("our nation" in Korean), gained more than 8,500 followers in a week though it posted just 30 tweets linking to reports praising North Korean leader Kim Jong Il and lambasting South Korea and the U.S. over ongoing joint military drills.
Uriminzok has "content that praises, promotes and glorifies" North Korea that was confirmed to be "illegal information" under South Korea's National Security Law, a commission statement said Thursday. The commission said it has no immediate plan to block the North's YouTube channel.
A South Korean government warning saying "Illegal content" pops up when an attempt is made to access the Twitter account in South Korea.
Commission official Han Myung-ho said the new Facebook account could be subject to the same fate.
"We are aware of the Facebook account and the police and the National Intelligence Service are currently investigating the site to verify whether it is indeed run by the North Korean government," Han said Friday.
"If we find that this Facebook account also carries content violating the National Security Law, we will do our duty of shutting it down as well."
The Facebook account, which describes itself as male, says it is interested in men and is looking for networking. The account had 50 friends as of Friday.
Its profile picture is of the Three Charters for National Reunification Memorial Tower, a 100-foot (30-meter) monument in Pyongyang that "reflects the strong will of the 70 million Korean people to achieve the reunification of the country with their concerted effort," according to the official Korean Central News Agency.
The Facebook account calls itself "a page representing the intentions of North and South Koreas and compatriots abroad, who wish for peace, prosperity, and unification of our homeland."
There were over 50 posts on Uriminzokkiri's wall, including links to reports that criticize South Korea and the U.S. as "warmongers," photos of picturesque North Korean landscapes, and a YouTube video of a dance performance celebrating leader Kim Jong Il, "guardian of the homeland and creator of happiness."
More than 130 videos have been uploaded to North Korea's YouTube channel, including clips that condemn and mock South Korea and the U.S. for blaming North Korea for the sinking of a South Korean warship in March. The North has insisted it had nothing to do with the sinking, which killed 46 South Korean sailors.
State Department spokesman P.J. Crowley said Tuesday that the U.S. welcomed North Korea to the social media forums but challenged its authoritarian leaders to allow its citizens full access to the sites.
North Korea, one of the world's most secretive countries, blocks Internet access for all but the elite among its 24 million citizens but is believed to have a keen interest in information technology.
The official North Korean Uriminzokkiri website, run by the North's Committee for the Peaceful Reunification of the Fatherland, has been blocked in South Korea alongside 64 other North Korean-run and pro-North Korean websites, says Shim Joo-hyung, a spokeswoman for the standards commission.