Japan says China has shipped drilling equipment to a disputed gas field in the East China Sea, fuelling diplomatic tensions between the Asian giants. China has previously refrained from unilateral drilling at Japan's request. Both Beijing and Tokyo claim exploration rights over the area. China scrapped scheduled talks with Japan over joint exploration of the field last week after Japan arrested the captain of a Chinese trawler near disputed islands in the East China Sea. All have been released except the captain who remains in detention. The Chinese fishing boat reportedly rammed Japanese coastguard patrol boats which had been trying to intercept it.