Japan has officially protested China's apparently planned gas field development in the East China Sea.
The Ministry of Foreign Affairs in Tokyo announced on Friday that it had received confirmation of Beijing's construction activities in the disputed sea area and had therefore submitted a protest note to the Chinese embassy.
The projects are therefore located in an area in which the exclusive economic zones (EEZ) claimed by China and Japan overlap.
US President Joe Biden, who is currently making his first trip to Asia since taking office, is expected in Japan on Sunday.
Dealing with China is likely to be a major topic in his talks.
Implementation of the agreement suspended
Tokyo and Beijing concluded a bilateral agreement in 2008 that provided for the joint development of gas reserves in the sea by both countries.
According to the agreement, neither country can unilaterally drill in the disputed area.
However, two years after the agreement, negotiations on the implementation of the agreement were suspended.
"It is extremely unfortunate that the Chinese side unilaterally proceeds with development in the waters," the Japanese Foreign Ministry said.
The border dispute in the East China Sea still has to be settled.
The ministry called “with great emphasis” for the “early resumption” of negotiations on the implementation of the 2008 agreement.
Japan accuses China of placing 17 suspected oil rigs near its de facto sea border.
The oil rigs are therefore on Chinese territory, but Japan fears that gas could also be extracted from Japanese waters from there.
China and Japan are also locked in a border dispute over the Senkaku Islands.
Further border conflicts exist between China and the other countries bordering the South China Sea.