TOKYO -- Japan renewed its territorial claim to South Korea's easternmost islets of Dokdo in teaching materials posted on a government website Sunday in a move that could draw a protest from Seoul.

The materials made by Saitama Prefecture claimed that Dokdo is Japanese territory and South Korea's occupation of the islets is illegal. South Korea has kept a small police detachment on Dokdo since 1956.

Other materials made by Shimane Prefecture -- which claims administrative sovereignty over the rocky islets -- include photos of Takeshima Day.

There was no immediate reaction from South Korea on Sunday.

In 2005, Shimane Prefecture designated Feb. 22 Takeshima Day to try to bolster Japan's territorial claim to the rocky outcroppings. Takeshima is the Japanese name for Dokdo.

The latest move is a follow-up to Japan's revised education guidelines in March that call for teaching students in elementary and middle schools that Dokdo belongs to Japan.

Japan's claim of sovereignty over Dokdo has long been a key source of diplomatic friction in relations with South Korea, where many people still harbor deep anti-Japanese resentment for its brutal 1910-45 colonial rule.

South Korea and Japan are close economic partners and key allies of the United States, though they have long been in conflict over territory and other historical disputes stemming from Japan's colonial rule of the Korean Peninsula. (Yonhap)