TOKYO (AFP) - Three Chinese government ships entered the waters of disputed Tokyo-controlled islands on Monday, Japan's coastguard said, as a long-running row shows no sign of fading.
Maritime surveillance vessels were spotted in the 12-nautical-mile zone off the Senkaku islands, which China calls the Diaoyus, in the East China Sea shortly after 9.00 am local time, the coastguard said.
They remained in the zone as of 7.00 pm local time, the coastguard added.
It is the latest episode in a fraught few months that has seen repeated stand-offs between official ships from both sides as they have jostled over ownership of strategically-important and resource-rich islands.
In a separate maritime incident in the East China Sea, a foreign submarine was spotted sailing underwater near Kume, one of Japan's Okinawan islands, from late Sunday to early Monday, the Defence Ministry said.
The submarine was thought to be Chinese, Japanese media said.
It sailed close to 12-nautical-mile territorial waters off Kume, alarming Japanese officials, although it did not violate international law.
"The situation is worth attention," Chief Cabinet Secretary Yoshihide Suga told a regular press briefing, noting that a foreign submarine was also spotted on May 2 near the Japanese island of Amami on the fringe of the East China Sea.
Defence Minister Itsunori Onodera said the self-defence forces would demand that the submarine spotted in the latest incident should come to the surface and show the flag of its nationality if it enters Japan's territorial waters.
The territorial row blistered in September when Tokyo nationalised three islands in the chain, in what it said was a mere administrative change of ownership.
Tokyo's move prompted angry anti-Japan demonstrations across China, which has intensified claims to the islands it says should have been "returned" in the post-World War II settlement made by Tokyo.
In one of the more intense incidents, Chinese warships locked their weapons-targeting radar on a Japanese destroyer, and opposing fighter planes have shadowed each other on numerous occasions amid warnings a slip-up could lead to a military showdown.
In late April, eight Chinese government vessels sailed into the disputed waters and Japanese Prime Minister Shinzo Abe vowed he would "expel by force" any Chinese landing on the islands.