[Getty/Kyodo]

SEOUL - Some South Korean lawmakers on Saturday visited disputed islands in the Sea of Japan controlled by Seoul and claimed by Tokyo, a local broadcaster reported, in a move sure to further escalate tensions between the Asian neighbors.

Their visit comes at a time when the two countries' relations have sunk to their lowest point in years following a series of South Korean court rulings ordering compensation for people claiming they were victims of forced labor during Japan's colonial rule of the Korean Peninsula from 1910 to 1945 and Japan's move to impose trade restrictions.

The lawmakers said on Friday they would visit the islands, known in Japan as Takeshima and in South Korea as Dokdo, in protest against Japan's claim to the islets.

The Japanese Foreign Ministry said it lodged a protest with South Korea.

Kenji Kanasugi, director general of the Foreign Ministry's Asian and Oceanian Affairs Bureau, told Kim Kyung Han, political minister at the South Korean Embassy in Japan, that the islands are "an inherent territory of Japan in light of historical facts and international law" and such a visit is "unacceptable," according to the Japanese Foreign Ministry.