China is brushing off a diplomatic protest by Japan over gas exploration in the East China Sea.

"They are totally within the scope of China's sovereign rights and jurisdiction," Foreign Ministry spokesman Geng Shuang told a regular news briefing Thursday, referring to the ongoing exploration activities in waters where the two nations have not agreed on an official boundary between their exclusive economic zones.

The Chinese reaction came a day after the Japanese government disclosed that it had filed the complaint, saying it was made after flares were witnessed this month at two of the 16 exploration platforms set up by China in the East China Sea near Japan's proposed median line separating the EEZs.