Work to excavate the remains of Chinese soldiers killed during the 1950-53 Korean War will take several months, a Seoul diplomatic source said Tuesday, adding South Korea aims to repatriate all of the remains to China by the end of next June.

South Korea started excavating the remains of 425 Chinese soldiers buried at a military-controlled cemetery in Paju, a border city with North Korea, last week under an agreement reached with China earlier this month.

"Excavation began last week as a preparatory step to return the remains, and we plan to complete the returning of the remains to China by the first-half of next year," the source said on the condition of anonymity.

China has also agreed on the timetable, the source said.

It will take time for South Korea to finish the entire process, including washing the remains and placing them in coffins, before returning them to China, according to the source.

This month's agreement, which came after South Korean President Park Geun-hye proposed it during her visit to China in June this year, has been described as a symbolic milestone in relations between the two former war adversaries.

The Korean War broke out on June 25, 1950 when tank-led North Korean troops invaded South Korea. The United States and 20 other allied countries fought on the side of South Korea under the United Nations flag, while Chinese soldiers came to help North Korea in the war. The conflict ended in a ceasefire three years later. (Yonhap News)