The North's state TV broadcast photos of Kim at the meeting, where he warned the North would not avoid war should it happen.

Kim also added that South Koreans should no longer be referred to as fellow countrymen.

The South's President Yoon Suk Yeol hit back at the North hours later.

"North Korean authorities defined South and North Korea as two hostile countries, not same-race countries. This shows the North Korean regime acknowledging their nature as anti-national and ahistorical."

In his speech to North Korea's rubber-stamp parliament, the Supreme People's Assembly - Kim added unification with the South was no longer an option.

The North's state TV also quoted him saying three organizations in charge of unification and inter-Korean tourism would be shut down.

Kim's call for constitutional changes come as tensions have recently worsened in the Korean Peninsula.

There's been a series of missile tests and a push by Pyongyang to break with decades of policy and change how it relates to the South.