A boat carrying 13 activists from Hong Kong and mainland China left Japanese territorial waters in the East China Sea on Monday after an attempt to land on the disputed Senkaku Islands was thwarted by Japanese patrol boats, the coast guard said.

A support group in China said on its Web site that the protesters had abandoned plans to land on the uninhabited islands, known as the Diaoyu Islands in China, as many of them were suffering from seasickness.

Later in the day, the Chinese government voiced support for the activists. The Chinese Foreign Ministry reiterated Beijing's position that "the Diaoyu Islands and its adjacent islets" have been "an integral part of China" since ancient times.