North Korean leader Kim Jong Un hosted a massive celebration to congratulate his nuclear scientists and technicians who steered the country's sixth and largest nuclear test a week ago, its official news agency said on Sunday.

South Korea had been bracing for another long-range missile launch in time for the 69th anniversary of North Korea's founding on Saturday, but no fresh provocations were spotted while the North held numerous events to mark the holiday.

Throughout last week, South Korean officials had warned the North could launch another intercontinental ballistic missile in defiance of U.N. sanctions and amid an escalating standoff with the United States.

Washington told the U.N. Security Council on Friday to call on a meeting on Monday to vote on a draft resolution establishing additional sanctions on North Korea for its missile and nuclear programme.

To laud the nuclear scientists and other top military and party officials who contributed to the nuclear bomb test last Sunday, Kim threw a banquet, KCNA said, topped with an art performance and a photo session with the leader himself.

KCNA did not specify when the banquet had been held, but analysts said it had likely been on Saturday.

Photos released on Sunday by KCNA showed the young leader breaking into a broad smile at the People's Theatre with two prominent scientists: Ri Hong Sop, head of North Korea's Nuclear Weapons Institute, and Hong Sung Mu, deputy director of the ruling Workers' Party of Korea's munitions industry department.

Ri and Hong have played vital roles in the North's nuclear programme, appearing at close distance to Kim during field inspections and weapons tests, including the latest nuclear test. Ri is a former director of Yongbyon Nuclear Research Centre, North Korea's main nuclear facility north of Pyongyang, where Hong also worked as a chief engineer.

North Korea had said the latest test was an advanced hydrogen bomb. There was no independent confirmation but some Western experts said there was enough strong evidence to suggest the reclusive state has either developed a hydrogen bomb or was getting very close.

KCNA said on Sunday the scientists and technicians "brought the great auspicious event of the national history, an extra-large event through the perfect success in the test of H-bomb".

Kim praised the developers in his own remarks as "taking the lead" in attaining the "final goal of completing the state nuclear force" in line with his parallel pursuit of nuclear and economic development.

"The recent test of the H-bomb is the great victory won by the Korean people at the cost of their blood while tightening their belts in the arduous period," Kim was quoted as saying.

Ri and Hong's roles have also been noted overseas, prompting the United Nations, the United States or South Korea to blacklist them.

Aside from the elite, rank-and-file North Koreans also commemorated the anniversary on Saturday by visiting the Kumsusan Palace of the Sun, which houses the embalmed bodies of founding father Kim Il Sung and his son and successor Kim Jong Il.

KCNA said servicepersons and civilians, including children, laid floral baskets and bouquets at the statues of the deceased leaders across the country, while enjoying art performances and dancing parties.