The Ministry of National Defense on Wednesday observed a memorial service to enshrine the remains of 20 former South Korean commandos who were trained to infiltrate North Korea but instead killed themselves in revolt against the government decades ago.

At the ceremony held at an Army facility in Byeokje near Seoul, the soldiers' families and military officials paid tribute in front of urns containing the remains of the 20 former agents and memorial tablets for two others whose remains have not been found.

The former commandos belonged to a 31-member military unit that South Korea set up in April 1968 to carry out a mission to assassinate then North Korean leader Kim Il-sung, the grandfather of current leader Kim Jong-un. With the camp established on Silmido, a barren islet off Incheon, west of Seoul, the "684" unit was launched following a botched attempt by North Korea the same year to assassinate then South Korean President Park Chung-hee.

Seven of the 31 agents either died or were killed by fellow unit members during the training.

On Aug. 23, 1971, the remaining 24 agents escaped from the islet after learning their mission was called off amid a thaw in inter-Korean relations.

Feeling betrayed by the government and angry, the would-be assassins rebelled against the authorities to call the public's attention to their harsh training and unfair treatment.

The heavily armed commandos, riding in a bus they had hijacked, were stopped at Yeongdeungpo in southern Seoul. After a gun battle with South Korean special forces troops, they blew themselves up with grenades. Four surviving commandos were court-martialed and sentenced to death in 1972, but their bodies have yet to be found.

A Defense Ministry committee tasked with investigating the incident unearthed the remains of the 20 commandos, who were killed in the street battle, in December 2005.

The ministry agreed with the bereaved families to install a separate facility where their remains will be enshrined and articles left behind by them will be on display. (Yonhap)