Four Chinese government ships temporarily sailed into the territorial waters of disputed Tokyo-controlled islands in the East China Sea on Sunday, Japan's coastguard said.

The maritime surveillance vessels entered the 12-nautical-mile zone around Uotsurijima, the main islet in the disputed chain called the Senkaku Islands in Japan and the Diaoyu Islands in China at about noon (0300 GMT).

The four ships left the zone at about 3:00 pm (0600 GMT) and remained within 24-nautical-mile "contiguous" waters off Uotsurijima at 3:30 pm ( 0630 GMT), a coastguard official said.

Japanese Vice Foreign Minister Chikao Kawai "strongly protested to the Chinese ambassador Cheng Yonghua about the Chinese ships' intrusion into Japan's territorial waters, and the growing frequency of such moves" by telephone, the foreign ministry in Tokyo said in a statement.

Kawai said the "repeated provocative action" would undermine communication between the countries aimed at calming the situation, according to the statement.

The Chinese envoy repeated Beijing's own view on the issue but added he was seeking to resolve the dispute through dialogue, it said.

Chinese vessels have moved in and out of what Japan says is its sovereign territory over the past two months since Tokyo nationalised some of the islands in the group.

It was the third consecutive day that Chinese vessels have entered the territorial waters of the disputed islets.

On Friday, six Chinese government ships temporarily entered the territorial waters around the same islet, while on Saturday, one Chinese government ship temporarily entered the same area, according to the coastguard.

As well as the potential mineral reserves, national pride is at stake in the decades-old spat, which has recently spiked and hit the huge trade relationship between the two biggest economies in the region.

Japan and China are readying for a third round of talks on the issue, but Japanese Prime Minister Yoshihiko Noda is not likely to hold bilateral talks with Chinese Prime Minister Wen Jiabao on the sidelines of an Asia-Europe summit in Laos opening on Monday, reports have said.

Noda will mention the importance of observing international laws to resolve territorial issues at the Asia-Europe summit, the premier told local media Sunday, adding how to improve "the ties with China and South Korea all comes down to level-headed discussions," Jiji Press reported.

Japan is also embroiled in a separate row with South Korea over a different set of disputed islands in the Sea of Japan, known as the East Sea by Koreans.