Tokyo: Japan said on Monday it had lodged a protest with China after spotting two of its fisheries patrol boats near a disputed island chain that is at the centre of a bitter row between the Asian giants.
"Last night around 9:00 pm (1200 GMT) our coastguard sighted them and afterwards the two (ships) left there and sailed north toward China," Japan`s top government spokesman Yoshito Sengoku said on Monday.
"After the incident we launched a protest through diplomatic channels," Sengoku, the chief cabinet secretary, told a regular press conference.
Beijing and Tokyo have been locked in their worst spat in years that started after Japan arrested a Chinese trawler captain on September 08 near the uninhabited island chain in the East China Sea.
Amid the row nationalist street demonstrations have been held in both countries, with protesters again rallying in China at the weekend, chanting anti-Japanese slogans and calling for boycotts of Japanese goods.
The row started when Japan arrested the Chinese captain near the Japan-administered islands, known as Senkaku in Japan and Diaoyu in China, after his ship had collided with two of its coastguard vessels.
China reacted with a barrage of diplomatic protests and snubs and other punitive steps and first dispatched two of its own fisheries patrol boats on September 23 to waters near the islands.
It withdrew the boats after Japan released the captain, but last week Japanese media reported that China had again dispatched boats on October 14, with the aim of "protecting the legal rights of Chinese fishermen".
The two economic giants and major trade partners have at various times sought to de-escalate the row.
Japan`s Prime Minister Naoto Kan held a brief meeting with Chinese Premier Wen Jiabao in Brussels early this month, and officials in Tokyo say both countries are seeking to arrange a formal summit later this week in Vietnam.