Japanese education chiefs will for the first time instruct schools to teach children that islands disputed with China and South Korea belong unequivocally to Tokyo, the government said Tuesday.

The announcement immediately prompted anger in Seoul, which called in the Japanese ambassador and warned of "reciprocal countermeasures" if the changes are not withdrawn immediately.

Revised teachers' manuals for junior and senior high schools will be issued to education boards across the nation, a Japanese education ministry official said.

"From the educational point of view, it is natural for a state to teach its children about integral parts of its own territory," Education Minister Hakubun Shimomura told a news conference.

The move comes as Prime Minister Shinzo Abe has stirred controversy with his unabashed nationalism, including a visit to a war shrine widely viewed by neighbouring countries as a symbol of Tokyo's wartime aggression.

Japan is embroiled in a row with China over the Tokyo-controlled Senkaku islands in the East China Sea, claimed as the Diaoyus by Beijing.

The dispute regularly sees standoffs between paramilitary ships and has also involved military vessels and planes. Some observers say the islands represent a key fault line for the region and could be the spark for an armed conflict.

Beijing's reaction was muted, with foreign ministry spokeswoman Hua Chunying saying the Chinese government was "severely concerned" and had launched "solemn representations".

"We want to stress that the Diaoyu islands and their affiliated islands have been China's inherent territory since ancient times," she said.

Tokyo and Seoul, meanwhile, are at odds over the sovereignty of a pair of sparsely-inhabited rocks in waters between them, administered by Seoul as Dokdo but claimed as Takeshima in Japan.

The new manuals describe both sets of islands as "integral parts of Japanese territory" for the first time, the official said.

The manuals will also note that the Takeshima islands are "illegally" occupied by South Korea, and that Japan does not even recognise the existence of a territorial dispute over the Senkaku islands, the official said.

The current manuals instruct teachers only to refer to a difference in Japanese and South Korean positions on Takeshima, while there were no remarks on the Senkakus.

"We called in the ambassador to lodge a strong protest ... after the Japanese education ministry maliciously included groundless allegations in textbook teaching manuals," South Korean Vice Foreign Minister Kim Kyou-Hyun told reporters invited to witness the convocation of Ambassador Koro Bessho.

A separate foreign ministry statement accused Japan of "holding on to its past bad habit of distorting history and nostalgia over past imperialism".

Japan's 1910-45 colonial rule over the Korean peninsula remains a hugely emotive issue in South Korea, which feels successive Japanese governments have failed to properly apologise or atone for abuses during the period.

The island dispute is seen by most South Koreans as evidence of Japan's continuing bad faith.

The new manuals will be used for junior high school social studies and high school geography, history and civics classes, starting in April 2016, the Japanese official said.

The manuals are not mandatory but teachers are advised to follow them when planning lessons.

In 2008, South Korea lodged a protest against Japan's reference to Takeshima in the school teaching manuals and briefly recalled its ambassador from Japan.

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