A researcher here said Sunday that she found multiple documents published by China in the 1900s that describe South Korea's ownership of the easternmost islets of Dokdo, which are also claimed by Japan.

Yoo Mi-rim, a researcher at the Korea Dokdo and Marine Territory Research Center under the state-run Korea Maritime Institute, published a book with multiple diplomatic documents she found in the archives of the Chinese foreign ministry.

The documents were estimated to be written between Korea's liberation from Japan in 1945 and the trusteeship by the Soviet Union and the United States in 1947 in order to present their idea about how to deal with the Korean territory. 

"Dokdo is located northeast of Ulleung Island. It is not big, and belongs to Ulleung Island," an excerpt from the Chinese data showed, citing South Korea's island located 87.4 kilometers northwest of Dokdo.

"Ulleung Island, Dokdo, and Jeju Island originally belong to Korea. In legal and moral principles, we have to of course say that they belong to Korea. During the trusteeship, the three islands should be governed by the United States or China," it showed.

This marks the first discovery and publication of diplomatic documents from China that illustrate the country's understanding

about the Korean territory.  

"The Chinese government banned me from copying them, and I had to transcribe the documents by hand. But I think the discovery holds significance, as the data give us a chance to learn China's recognition of the territory," Yoo said. Her new book is titled "Dokdo and Ulleung Island in our historical data."

The Korean Peninsula was put under the trusteeship of the U.S.

and the Soviet Union following its liberation from Japan's colonial rule (1910-45) at the end of World War II.

South Korea reclaimed sovereignty over its territory, including Dokdo and many other islands around the Korean Peninsula, upon gaining its independence from Japan.

Japan, however, has made repeated claims to Dokdo, souring relations between the two neighbors. (Yonhap News)