Tokyo complained to Pyongyang Saturday as North Korea test-fired seven missiles into the Sea of Japan, officials said.

The Japanese government filed an official diplomatic complaint with North Korea through Chinese channels in Beijing as the South Korean Joint Chiefs of Staff spotted the seventh missile firing of the day, the South Korean news agency Yonhap reported.

Japanese Chief Cabinet Secretary Takeo Kawamura said in a statement Saturday, "It is a serious act of provocation against the security of neighboring countries, including Japan, and is against the resolution of the U.N. Security Council."

The Japanese news service Kyodo reported that Prime Minister Taro Aso is set to urge leaders at Group of Eight Summit in Italy to keep working together to deal with North Korea's nuclear and missile development issues.

Pyonyang also test-fired four missiles into the Sea of Japan on Thursday, the Chinese news agency Xinhua said.