The advertisement, which lasted nearly three minutes after a news programme on Thursday, showed a grinning Korean man with sweat on his face holding a glass of beer, with a caption that read: “Taedong River Beer is the pride of Pyongyang.”

The commercial said the beer relieves stress and improves health and longevity. It also showed images of a pub it said was in the capital of Pyongyang, filled with people drinking. Normally, there are no advertisements on television in North Korea, an isolated, Communist country that tightly controls its economy and is wary of capitalistic influences.

Programming consists of news, factory descriptions, some children’s animation shows, and documentaries on leader Kim Jong Il and his father Kim Il Sung, interspersed with propaganda slogans and music, according to a South Korean Unification Ministry official.

The official, who has been monitoring the North’s television for more than two decades, said that it was the first time he had seen any sort of advertisement for food, much less beer — although he has seen programmes on North Korean cuisine.

The commercial assured viewers of the beer’s quality and nutritional value, saying it was made of rice and contained protein and vitamin B2.

It was unclear how much the beer cost and how many North Koreans could afford it. The country is among the poorest in the world, with an average per capita income of $1,065 in 2008, according to the South’s Central bank.

Kim Jong Il, the North Korean leader, apparently enjoys beer.

Kenji Fujimoto, a Japanese sushi chef for Kim, said in a 2003 memoir that he traveled the world for the leader, buying Czech beer as well as Chinese melons, Danish pork and Thai papayas.