Tokyo lodged a protest with Beijing after an "unaccepable" request to stop conducting marine research was issued to a Japan Coast Guard ship operating in Japan's exclusive economic zone, Chief Cabinet Secretary Osamu Fujimura said Monday.
"We told China via diplomatic channels that we are conducting legitimate marine research within our EEZ and the activity cannot be halted," Fujimura said in a news conference.
A Chinese government vessel radioed the coast guard survey ship Shoyo and called on it to stop its activities at around 7:20 p.m. Sunday when the ship was studying crustal structures about 170 km north-northwest of Kumejima Island in Okinawa.
Shoyo replied via radio that the research was legitimate and conducted within Japan's EEZ.
The Chinese ship continued to make the request for about 20 minutes.