Kim also set out a five-year plan to boost economic growth, emphasizing the need to improve North Korea's electricity supply, the official Rodong Sinmun newspaper said, Reuters writes.

The North "will faithfully fulfill its obligation for non-proliferation and strive for the global denuclearization," Kim said in a report to a rare congress of the ruling Workers' Party that opened on Friday, the KCNA news agency reported.

The first congress in 36 years began amid anticipation by the South Korean government and experts that the young third-generation leader would use it to further consolidate power.

As reported earlier, North Korea came under toughened new U.N. sanctions in March after its most recent nuclear test and the launch of a long-range rocket that put an object into space orbit in defiance of past Security Council resolutions.

Since then, it has continued to engage in nuclear and missile development activities and claimed that it had succeeded in miniaturizing a nuclear warhead and launching a submarine-based ballistic missile.

In March, Kim said the North would soon test a nuclear warhead, and South Korea has said Pyongyang may conduct its fifth nuclear test in conjunction with the party congress.