Japan tightened security around disputed islands and restated its ownership of the chain, a year after its nationalisation of the islands triggered a bitter row with China.
Tensions remain high with Beijing, which sent several coastguard boats to patrol around the islands on Tuesday.Japan bought the islands, known as Senkaku in Japan and Diaoyu in China, from their private owner a year ago.
China has described the purchase as invalid.
It says it has conducted 59 patrols near the islands since then - its vessels sailing in and out of what Japan says are its territorial waters.
On Wednesday, Japanese Chief Cabinet Secretary Yoshihide Suga reiterated Japan's claim to the islands.
China has described the purchase as invalid.
It says it has conducted 59 patrols near the islands since then - its vessels sailing in and out of what Japan says are its territorial waters.
On Wednesday, Japanese Chief Cabinet Secretary Yoshihide Suga reiterated Japan's claim to the islands.
Defence Minister Itsunori Onodera said surveillance had been increased in the islands' area but gave no details, the Associated Press news agency reported.
Coastguard official Yuma Miyako, meanwhile, told AFP that the agency was on "high alert" for the anniversary.
"We are preventing Chinese official ships from entering our territorial waters, with our ships sailing very close to the Chinese ships," the official said.
