TOKYO (AFP) - Three Chinese government ships entered waters around disputed islands controlled by Tokyo on Sunday, Japan's coastguard said.

The Chinese maritime surveillance vessels were spotted inside the 12-nautical-mile zone off the Senkaku islands, which China calls the Diaoyus, in the East China Sea shortly after 10am (9am Singapore time), the coastguard said.

They left the zone at 3.14 pm, it said later.

Territorial waters extend by a maximum of 12 nautical miles from coastlines under international law.

The move marked the latest in a long line of stand-offs between official ships from both sides as Beijing and Tokyo jostle over ownership of the strategically important and resource-rich islands.

A long-simmering territorial row that dates back four decades blistered in September when Tokyo nationalised three islands in the chain, in what it said was a mere administrative change of ownership.

The central government's move was intended to pre-empt a purchase by the Tokyo city government led by nationalist governor Shintaro Ishihara at the time.

Tokyo's move prompted angry anti-Japan demonstrations across China, which has intensified claims to the islands it says should have been "returned" after World War II.