Japan has filed a protest with South Korea over a plan to place a “comfort women” memorial statue on disputed islets in the Sea of Japan, Chief Cabinet Secretary Yoshihide Suga said.

The plan is “extremely deplorable and unacceptable in light of our position on the sovereignty of Takeshima,” Chief told a news conference Tuesday, referring to the islets controlled by South Korea but claimed by Japan.

A group of South Korean local assembly members announced Monday they plan to place the statue on the islets — called Dokdo in South Korea — according to South Korean media, following weeks of heightened tensions over the issue of the women procured for Japanese military brothels before and during World War II.

A statue dedicated to the women outside the Japanese Embassy in Seoul, depicting a girl in traditional Korean clothing sitting beside an empty chair, has irked Japan since it was erected in 2011.

In a landmark deal in December 2015, aimed at settling the comfort women issue, South Korea said it would “strive to solve” the matter of the Seoul statue “in an appropriate manner.”

But tensions flared late last month when a statue of the same design was put up in front of the Japanese Consulate General in the southern port city of Busan. In response, Japan recalled its ambassador, who has yet to return to South Korea.

Foreign Minister Fumio Kishida called the latest statue plan “unacceptable.”

“In the first place, Japan’s position is that Takeshima is our inherent territory, both under international law and historically,” Kishida told a news conference Tuesday.

South Korea promptly lodged a protest over Kishida’s remarks, with Foreign Ministry spokesman Cho June-hyuck saying it was “deeply deplorable that Japan, once again, made the unjust (territorial) claim.”

Speaking at a press briefing, Cho urged Japan to “halt repeating the futile claim over the territory, which is clearly an integral part (of South Korea).” South Korea has controlled the islets since the 1950s.

The assembly members from Gyeonggi province in South Korea’s northwest said they will raise funds for the statue, aiming to erect it on the tiny islets by December, according to South Korean media reports.

Many of the women procured for Japanese military brothels were from the Korean Peninsula, which was under Japanese rule from 1910 to 1945. A Japanese government study in the early 1990s concluded that many of the women were procured against their will.