Seoul: North Korea marked the birthday of its late founder and eternal president with acrobats, street dancing and boasts of building a bigger nuclear arsenal yesterday.

For North Koreans, the anniversary of the birth of Kim Il-sung is a time for festivities and perhaps a little larger rice ration than usual. For regional powers, though, it serves as a reminder of the difficulties of ending Pyongyang's atomic ambitions that were launched decades ago under his leadership.

North Korea calls the holiday the Day of the Sun. Kim, known as the "Great Leader", died in 1994 and was succeeded by his son, Kim Jong-il, establishing the world's only communist dynasty.

At an event to mark the anniversary, the man considered to be the North's current number two leader said the United States would try at all costs to bring down the communist state, known officially as the Democratic People's Republic of Korea.

"It is the legitimate right of the DPRK to self-defence to bolster up its military deterrent in every way to cope with the prevailing grave situation," Kim Yong-nam said in a report carried on the North's official KCNA news agency.

In numerous official media reports, North Korea has said it is building a nuclear deterrent to counter what it views as Washington's hostility towards it.

Kim Yong-nam also told the gathering the country was still trying to find its way out of a food shortage that plagued the final years of Kim Il-sung's reign.

"In this year, too, we should regard agriculture as the main front of the economic construction and mobilise and concentrate all forces on farming once again and thus bring a bumper harvest to the land of socialist Korea to fully solve the food problem."

Most reports in official media at the weekend spoke of celebrations, such as floral shows attended by foreign dignitaries.