China on Monday slammed a reported plan by Japan to revise guidelines for school textbooks to bolster its territorial claims to a set of islands in the East China Sea at the center of a bitter dispute with Beijing.

China's foreign ministry spokeswoman Hua Chunying made the remarks in response to Japanese media reports that Tokyo was considering revising the guidelines to describe the islands, known as Diaoyu in China and Senkaku in Japan, as Japan's "indigenous territory."

The reported move by Japan is also an issue in South Korea because Tokyo is considering using the same description for Seoul's easternmost islets of Dokdo.

"We urge Japan to not underestimate the Chinese government's determination and resolve in defending China's territory and sovereignty," Hua said at a daily briefing.

"If Japan takes a further provocative action on the issue of Diaoyu islands, China will make a firm response," Hua warned. "And the Japanese side will be responsible for all the consequences arising from that."

South Korea's Foreign Ministry summoned a Japanese diplomat in Seoul on Sunday to verify the Japanese reports.

It was not immediately known how the Japanese diplomat responded, but a senior official at the Korean ministry warned that, if the reports are true, it would further damage bilateral relations between Seoul and Tokyo.

Dokdo, which lies closer to South Korea in the body of water between the Korean Peninsula and Japan, has long been a thorn in relations between the two countries. South Korea keeps a small police detachment on the islets, effectively controlling them. (Yonhap News)