North Korean leader Kim Jong Un has said he will not use nuclear weapons against other nations first unless his country's sovereignty is threatened.

Speaking at the first congress of North Korea's Workers' Party in 36 years the leader pledged that the country's nuclear arms will only be deployed in the face of hostilities against the nation.

He said: "As a responsible nuclear weapons state, our Republic will not use a nuclear weapon unless its sovereignty is encroached upon by any aggressive hostile forces with nukes."

According to ITV News China Correspondent Debi Edward, who is reporting from the secretive state during the congress, Kim Jung Un did send a message to the United States though warning them to "stay away from inter-Korean relations".

The leader's comments follows on from similar statements in the past and in spite of the fact that just weeks ago video emerged of North Korea conducting missile tests and firing rockets towards South Korea.