Japan said on Tuesday it was revising teaching manuals to make clear that two sets of remote islands at the centre of disputes with China and South Korea are integral parts of its territory, prompting protests from an angry Seoul.
Japan's ties with Seoul and Beijing are increasingly strained over a host of issues, including the territorial rows and Japanese Prime Minister Shinzo Abe's visit late last year to the Yasukuni Shrine, where convicted war criminals are honoured along with millions of war dead.
The conservative Abe has said he wants to revise Japanese history to have a less apologetic tone, a sensitive topic for Asian neighbours such as South Korea and China, where memories linger of Japanese aggression before and during World War Two.
Education Minister Hakubun Shimomura said the ministry was revising the manuals to teach "properly" about Japanese history and that it would make diplomatic efforts to explain the move to Japan's neighbours.
"It is extremely important that the children who will bear our future can properly understand our territory," he told a news conference.
He said the teaching manuals would be changed to make clear that the rocky islets controlled by South Korea but claimed by both nations, known as Takeshima in Japan and Dokdo in South Korea, were Japanese territory.
South Korea's Foreign Ministry promptly summoned the Japanese ambassador to protest.
Earlier, the Ministry called for Japan to repeal the changes, which it said were teaching children a false claim to the islets.
"Our government strongly condemns this and asks Japan to immediately withdraw it," it said in a statement.
The manuals will also add reference to the Senkakus, which are at the centre of a dispute with China, which calls them the Daioyus, and reiterate Tokyo's stance that these are an integral part of Japanese territory and there is no dispute over their ownership.
They will affect classes in history, geography and civics in junior and senior high schools, but are not legally binding.
Asked about the territorial rows, Shimomura said he felt it was too bad that there were competing claims to the islands and repeated that historically, the islands were part of Japan.
"We must make efforts to politely explain our position to both nations and seek their understanding," Shimomura said.
The announcement came just days after the head of Japan's public broadcaster triggered a furore in Asia with comments on military brothels during World War Two. On Monday he expressed regret, terming his remarks as "extremely inappropriate."
Both China and Korea suffered under Japanese rule, with parts of China occupied in the 1930s and Korea colonized from 1910 to 1945.