TOKYO (AP) — Japan has protested to Beijing over a Chinese survey ship that operated for 10 days inside the exclusive economic zone claimed by Japan around Okinotorishima, a tiny island in the Pacific Ocean, officials said Monday.

Japan says Okinotorishima — two uninhabited rocky outcroppings about 1,700 kilometers (1,060 miles) southwest of Tokyo — are islands. China says they are only rocks and do not qualify as a demarcation point for Japan's exclusive economic zone, as Japan claims under international law.

Chief Cabinet Secretary Yoshihide Suga told reporters that coast guard officials spotted a Chinese ship using survey equipment in the waters beginning July 9 and ordered it to stop. The Chinese ship stayed in the area until Saturday and Japan protested to Beijing via diplomatic channels, Suga said.

“We have not given permission to the Chinese side to conduct a maritime scientific survey in the waters,” Suga said. Japan says Okinotorishima anchors the country's EEZ under the United Nations Convention of the Law of the Sea, which requires foreign ships to gain prior consent to operate surveys or fishing.

Just the tips of the small outcroppings are visible at high tide. They have been heavily enhanced by concrete embankments to avoid further erosion. A few years ago, Japanese fisheries officials planted corals around the outcroppings in an attempt to enlarge them.

China does not dispute Japan's control over Okinotorishima, but has repeatedly criticized Tokyo's claim that it is an island.

On Friday, Chinese foreign ministry spokesperson Hua Chunying said Okinotorishima is a reef under the U.N. convention, not an island, so Japan cannot use it to claim an EEZ. Hua said the Chinese survey ship was exercising freedom of scientific research on the high seas and Japan's permission was not needed.

Japan and China have stepped up their territorial disputes recently.

China has ramped up its claim to Japanese-controlled islands called Senkaku in Japan and Diaoyu in Chinese. It also has been asserting his claim to most of the South China Sea, parts of which are claimed by several other regional governments.