Kim made the announcement at an event marking the 80th anniversary of the North Korean air force on Friday, accompanied by his daughter Ju Ae, who is understood to be his recognised successor.

"The Air Force will be given new strategic military assets and entrusted with a new important duty," he said in a speech without elaborating, according to state news agency KCNA.

"The Air Force should resolutely repulse and control all sorts of espionage acts and possible military provocations of the enemies," he added.

State media photos showed Kim and his daughter watching what is appeared to be jets performing manoeuvres in the sky.

Pyongyang has not responded to offers by South Korea for talks aimed at avoiding accidental military clashes along the two countries' shared border.

Seoul proposed this month that the two sides hold military talks to discuss the so-called Military Demarcation Line, citing repeated incursions by North Korean troops.

On Monday, South Korean President Lee Jae Myung said Pyongyang had taken "extreme actions" by installing triple layers of barbed-wire fences along the border.

"We have now reached a situation where we do not know when an accidental clash may occur," Lee warned.

"All lines of connection have been cut. They are refusing all dialogue and contact. It is a very dangerous state," he said.