South Korea says its troops have exchanged gunfire along land border with North Korea and that there are no injuries.

South Korea’s military has said its troops exchanged fire with North Korea along their tense land border.

The Joint Chiefs of Staff in Seoul said North Korean troops fired several bullets at a South Korean guard post inside the heavily fortified border between the two countries at 7:41 am on Sunday.

South Korea fired two rounds in response after issuing a warning broadcast, the military said in a statement, adding it suffered no casualties.

“We are taking actions via inter-Korean communication lines to grasp the detailed situation and to prevent any further incidents. And we also maintain a necessary readiness posture,” it said.

Sunday’s exchange of fire took place one day after North Korea reported its leader Kim Jong Un’s first public appearance in about 20 days amid intense speculation about his health.

North Korea’s official media published photographs and a report on Saturday that Kim had attended the completion of a fertiliser plant, the first report of his appearance since April 11.

The Koreas are split along the 248-kilometre-long, 4-kilometer-wide (154-mile-long, 2.5-mile-wide) border region called the Demilitarized Zone that was originally created as a buffer.

But unlike its name, the DMZ is the world’s most heavily fortified border. An estimated 2 million mines are peppered inside and near the DMZ, which is also guarded by barbed wire fences, tank traps and combat troops on both sides.

In late 2018, the two Koreas began dismantling some of their front-line guard posts and removing mines from the DMZ as part of steps to reduce tensions.

But the efforts stalled amid a deadlock in nuclear negotiations between Kim and President Donald Trump meant to convince North Korea to give up its arsenal in exchange for lifting economic sanctions.

The last time there was gunfire along the border was in 2017, when North Korea sprayed bullets at a soldier fleeing to South Korea.