BEIJING -- China rebuffed Japan's protests to its gas development in the East China Sea on Tuesday, and reiterated its sovereignty in the areas.

"China is conducting activities in the areas under undisputed Chinese administration. Japan's so-called 'protest' is unreasonable, and China will not accept such unreasonable demands, " said Foreign Ministry spokesperson Hua Chunying.

Hua made the remarks at a regular press briefing after Japan's Chief Cabinet Secretary Yoshihide Suga said on Monday that Japan has been protesting China's gas development in the East China Sea since June 2013.