Japan was expected to repeat its territorial claims over South Korea's easternmost islets of Dokdo in its annual diplomatic report, sources said Friday, just two days after Tokyo approved a series of textbooks claiming the islets as its territory.

Japan's Cabinet planned to approve the "Diplomatic Blue Paper" report for 2011 that was expected to carry the same territorial descriptions of Dokdo as its previous version, the sources said.

Tokyo has a consistent position that the islets are Japanese, the sources added.

Last year's report also said Japan is trying to promote its position through pamphlets while repeatedly delivering the stance to South Korea and that the country will make persistent efforts to bring a peaceful resolution to the issue.

South Korea is expected to summon a diplomatic minister at Japan's embassy in Seoul to file an official protest, officials said.

Japan first mentioned the Dokdo claims in the diplomatic report in 1963 and has since carried the claims in the book on an irregular basis without putting them in the reports issued in 1967-1970, 1988-1989, 1993-1996, 1998-1999, 2002 and 2007.

The move came after Tokyo licensed a dozen middle school textbooks Wednesday with enhanced claims over the islets compared with the previous versions of the texts. The number of textbooks claiming South Korea is "illegally occupying" Dokdo rose from one to four.

South Korea strongly protested the move and urged Japan to scrap the decision.

Foreign Minister Kim Sung-hwan immediately called in Japanese Ambassador Masatoshi Muto and lodged complaints. On Friday, Seoul's ambassador to Tokyo Kwon Chul-hyun was to make a protest visit to Japanese Foreign Minister Takeaki Matsumoto.

The series of Japanese moves came at a time when South Koreans have been pouring out sympathy and support for the former colonial ruler suffering from a devastating earthquake and tsunami.

But South Korea says humanitarian assistance is a different matter from the textbook issue.

Japan's claims over the islets have long been a thorn in relations between Seoul and Tokyo.

South Korea rejects the claims as nonsense because the country regained independence from Japan's 35-year colonial rule in 1945 and reclaimed sovereignty over its territory, including Dokdo and many other islands around the Korean Peninsula.

Since 1954, South Korea has stationed a small police detachment on Dokdo.

(Yonhap News)