Seoul, May 8 (IANS): South Korea discovered 11 more bone fragments, believed to be from soldiers killed in the 1950-53 Korean War, inside the Demilitarized Zone (DMZ) on the border with North Korea, the Defence Ministry said here on Friday.

The pieces were found during a de-mining and excavation operation under way on Arrowhead Ridge last week, Yonhap News Agency quoted the Ministry as saying.

The ridge located in Cheorwon, some 90 km northeast of Seoul, was one of the fiercest battlefields during the war.

Since April 20 when the military resumed the excavation project for this year, it discovered a total of 23 pieces of bones and 3,426 articles believed to have been left by the deceased service members, according to the Ministry.

It remains unclear how many people the pieces belonged to, and the authorities will carry out a detailed examination and DNA analysis to identify their origins, it added.

"We've also employed small-sized surveillance robots to search multiple trenches found on the site," the Ministry said.

Under a bilateral military accord signed on September 19, 2018, the two Koreas agreed to launch a joint excavation project on Arrowhead Ridge, reports Yonhap News Agency.

But the South has carried out the project alone since last year, as the North did not respond to calls for joint work.

Last year, the military found around 2,030 bone fragments believed to have belonged to about 261 troops killed in the war.

Of them, 117 sets of remains are believed to be of Koreans, with 143 others presumed to belong to Chinese troops and another set to .N forces, according to the Ministry.