Japan-China diplomatic tensions threatened to boil over Wednesday over collisions between Japan Coast Guard patrol boats and a Chinese fishing vessel near the Senkaku Islands and the ensuing arrest of the trawler's captain.

Both Beijing and Tokyo lodged protests over the incident. According to media reports, about 50 people staged a protest rally in front of the Japanese Embassy in Beijing, holding up banners, one of which read "Japan get out of Diaoyu Island," using the Chinese name for the disrupted territory.

During his regularly scheduled news conference Wednesday morning, Chief Cabinet Secretary Yoshito Sengoku called for calm.