North Korea blew up the inter-Korean joint liaison office in its border town of Kaesong on Tuesday, sharply escalating tensions on the Korean Peninsula after near-daily threats to punish Seoul over anti-Pyongyang propaganda leaflets.

The North exploded the liaison office at 2:49 pm, the unification ministry said.

Earlier, military sources said that smoke was seen and an explosion was heard from the border town, Yonhap news agency reported.

The explosion came just days after Kim Yo-jong, sister of North Korean leader Kim Jong-un, warned Saturday night, "Before long, a tragic scene of the useless North-South joint liaison office completely collapsed would be seen."

The North has been lashing out at the South for failing to stop defectors from sending anti-Pyongyang leaflets across the border via balloons, Yonhap reported.

The liaison office was launched in September 2018 to facilitate inter-Korean exchange and cooperation amid a reconciliatory mood created by summit talks between their leaders.

The two Koreas had suspended its operation since early January over concerns over the coronavirus pandemic. Last week, North Korea defined South Korea as an "enemy" and vowed to cut off all communication lines in anger over leaflets sent by activists in South Korea.

-- BERNAMA