Japan's Foreign Minister Taro Kono says Japan has protested to China over its gas field activity in the East China Sea.
The Foreign Ministry says a new mobile drilling rig was spotted earlier this month on the Chinese side of a median line that separates the 2 countries' exclusive economic zones. The rig is believed to have a deeper drilling capacity than others in the area. The ministry told the Chinese Embassy in Tokyo that unilateral development of gas fields cannot be tolerated.
Kono said China is taking this kind of action before the 2 countries agree on their maritime boundary. He said the activity will not benefit bilateral friendship.
Chief Cabinet Secretary Yoshihide Suga says the government will continue to press China to resume talks to implement at an early date the 2008 agreement to jointly develop gas fields in the East China Sea.
Talks for a treaty on a maritime boundary have been suspended since 2010. China has unilaterally continued with its oil and gas field development.
China denies that its activities are unilateral, saying that they are carried out in undisputed waters under Chinese jurisdiction.
Last October, a US think tank, the Center for Strategic and International Studies, reported that China had built 3 new rigs on the Chinese side of the median line in 2017. The finding brought the number of Chinese structures in the area to 19.