North Korea blows up a joint liaison office with South in Kaesong.

North Korea has blown up its joint liaison office with the South near the border town of Kaesong, South Korean officials say.

The move comes just hours after the North renewed threats of military action at the Korean border.

The site, which is in the North's territory, was opened in 2018 to help the two Koreas to communicate.

The liaison office has been empty since January due to Covid-19 restrictions.

Tensions between North and South Korea have been escalating for weeks, prompted by defector groups in the south sending propaganda across the border. The North Korean leader's sister, Kim Yo-jong, threatened to demolish the office in a statement at the weekend.

In recent weeks, North Korea has repeatedly condemned the South for allowing propaganda into its territory.

Defector groups regularly send such material via balloons, or even drones, into the North.

South Korea's Unification Ministry in Seoul confirmed that at 14:49 local time there was an explosion. Last Tuesday, Pyongyang announced it was severing all official communication links with Seoul.

Over the weekend, Kim Yo-jong threatened to send troops into the demilitarized zone (DMZ) at the inter-Korean border.

Then, before the explosion on Tuesday, the military leadership confirmed it was ready to "turn the frontline into a fortress".