The secretive, one-party state is currently led by Kim Jong Un - the third generation of the Kim family to rule North Korea. It was not immediately clear what exactly would be discussed at next month's congress, though South Korean analysts say Kim will likely use the convention as a chance to reshuffle top officials, reveal policy directions and further strengthen his grip on power.

State media, the Korean Central News Agency (KCNA), also failed to disclose how long the congress would last. The previous congress in 1980 brought together some 3,000 delegates from across the country and went on for five days.

KCNA reported that those attending next month's congress will have "fully displayed their intense loyalty and patriotic devotion to the development of the Party and the building of a thriving nation."

Tensions over missile tests

The announcement on Wednesday came just days after reports that the communist nation had launched a ballistic missile from a submarine in the Sea of Japan. According to KCNA, Kim Jong Un ordered the test launch and had deemed it a success.

US President Barack Obama condemned the North for its "continuous provocative behavior," while the UN Security Council said the incident constituted "yet another serious violation by North Korea of United Nations Security Council resolutions."

North Korean Foreign Minister Ri Su Yong said on Saturday that Pyongyang was ready to halt its nuclear tests if the US suspended its joint military exercises with rival South Korea.

"Stop the nuclear war exercises in the Korean Peninsula, then we should also cease our nuclear tests," he said in his first interview with a Western news agency.

Obama retorted by saying that the US did not take North Korea's promises seriously.

ksb/kms (Reuters, AP, dpa)