A long-running dispute over the ownership of a remote group of islands in the East China Sea has been reignited, after Japan's coastguard blocked a boat carrying Chinese activists from landing there on Monday.
Protesters from China and Hong Kong entered the disputed territory
The activists claim the uninhabited islands belong to China, but the incident has prompted Japan to reassert its own ownership claims.
The small island group - called Senkaku in Japan and Diaoyutai in China - lies in the East China Sea, between southern Japan and Taiwan.
A small Chinese boat carrying 13 protesters entered Japanese waters at around 0945 local time (0045 GMT), according to coastguard officials.
"The protesters read a statement from the vessel to our patrol
boat that disputed Japan's ownership claim of the island," the official said.
Japanese gunboats and aircraft headed off the convoy, and the coastguard official said the boat moved out of Japanese waters without a clash occurring.
Officials in Tokyo said on Monday that they would resist any unauthorised entry to the islands.
"Senkaku islands are an integral part of our own territory. There
is no doubt about this either historically or based on
international laws," said Chief Cabinet Secretary Yasuo Fukuda.
"We will take appropriate measures in line with the law," he said.
Japan first claimed the islands in 1895, and apart from a short period of US control after World War II, they have remained under Tokyo's control.
The dispute began in the early 1970s, when both China and Taiwan made claims to the islands after oil deposits were confirmed
in the area.
The islands also provide access to rich fishing grounds.
In 1996, Japanese right-wing extremists caused an outcry in neighbouring countries when they built a makeshift lighthouse on one of the islands.
The situation escalated in January, when the Japanese Government said it had leased three of the islands from a private owner.
Protests in China, Taiwan and Hong Kong followed, with China's ambassador to Japan, Wu Dawei, calling the lease "illegal and invalid".
David Ko, chairman of the Hong Kong-based Action Committee to Defend the Diaoyutai Islands, told the French news agency AFP that protesters would land on the islands every year, in protest at Japan's continued rule.