The Chinese maritime surveillance vessels were spotted off the Senkaku islands, which China calls the Diaoyus, in the East China Sea at around 2:30 pm (0530 GMT), the coastguard said.
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.
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 and one intended to pre-empt a more volatile purchase by nationalist Tokyo governor Shintaro Ishihara.
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 Tokyo made.
