South Korea condemned on Monday Japan's approval of textbooks that it said distorted history by claiming disputed islands, summoning Japan's ambassador and warning that the approval was a sign Japan was prepared to repeat its colonial wartime past.
The strongly worded protest came just over two weeks after the foreign ministers of the neighbors and China pledged to improve ties and overcome tension over history and territory, and to try to work for a summit meeting of their leaders soon.
South Korea's foreign ministry said the book approval was "yet another provocation that distorts, reduces, and omits clear historic facts to strengthen its unjust claims to what is clearly our territory".
"The Japanese government is in effect saying it will repeat its mistakes of the past when it injects distorted historical view and territorial claims based on that to a generation of Japanese who are growing up," it said in a statement.
South Korea controls the disputed islands, called Dokdo in Korean and Takeshima in Japanese, which have been the focus of a long dispute. South Korea sees Japan's claims as stemming from its colonial past.
Japan colonized the Korean peninsula from 1910 until Japan's World War Two defeat in 1945. Koreans remember Japanese rule with bitterness, saying many people were conscripted into forced labour and women were forced into military brothels.
South Korea's Yonhap news agency said Japan's education ministry had approved the geography textbooks that made a direct territorial claim over the islands.
Japanese Education Minister Hakubun Shimomura said all textbooks would have references to the islands as being part of Japan's territory.
"It's only natural that we want to teach children correctly about their country's territory," he told reporters in Tokyo.
Japan's ties with South Korea and China have long been marred over what South Korea and China see as Japanese leaders' reluctance to atone for its wartime past.
But Japanese Prime Minister Shinzo Abe has tried to ease tension.
Japan and China also have a dispute over East China Sea islands known as the Senkaku in Japan and the Diaoyu in China.
Japan-China ties remain cool despite Abe meeting Chinese President Xi Jinping for the first time last November. South Korean President Park Geun-hye has yet to have a two-way summit with Abe.
Leaders of the three countries have not met for what had been an annual three-way summit since May 2012 but their foreign ministers met last month, raising hope for better relations between the economic powers.