South Korea has launched a manhunt for a soldier who shot dead five of his comrades and fled his post near the border with North Korea.

The sergeant, identified only by his surname, Lim, opened fire on his colleagues on Saturday at the border town of Goseong, Gangwon province.

Seven other troops were injured in the incident, but are expected to survive.

It is not clear why the shooting began. There have been similar shooting cases in the South Korean army in the past.

Sgt Lim shot fellow members of his 22nd infantry division and then escaped with his rifle and some ammunition, army officials said.

'Difficulties adapting'

"A manhunt is underway to find him as early as possible and to prevent another incident from taking place," defence ministry spokesman Kim Min-seok said on Sunday.

Troops have been deployed to block possible escape routes, guard the border between North and South Korea, and protect areas where civilians live, officials said.

The army has told the media the military unit was in remote location and it believed the runaway soldier was still near by, the BBC's Kevin Kim in Seoul reports.

Guarding the demilitarised zone, which divides the two Koreas, is considered one of the toughest jobs for military conscripts, our correspondent adds.

South Korean news agency Yonhap said Sgt Lim "threw a grenade and then opened fire" after completing his day shift.

An officer said Sgt Lim "was on the list of those who require special attention, as he had difficulties in adapting to the military life," Yonhap reported, adding that he had been due to be discharged in three months.

The defence ministry spokesman said the incident was "regrettable", adding: "We truly apologise for causing concern to the nation."

There have been similar incidents in South Korea's military, which operates under a conscription system. Bullying and mental problems have been blamed for previous attacks.

In 2011, a marine opened fire on his colleagues and tried to blow himself up with a grenade. Four soldiers were killed in the attack.

Tens of thousands of soldiers from both North and South Korea are stationed along their joint border, one of the most heavily fortified in the world.

The two Koreas were divided at the end of the 1950-53 Korean War, which ended in an armistice rather than a peace treaty. As a result, they remain technically at war.

(BBC)