Amid a dispute over Japan's detention of a Chinese fishing boat captain, Beijing reportedly cuts off exports of so-called rare earth elements to Japan, which are used in high-tech products including hybrid vehicles. A day after China's premier warned that his nation would punish Japan if it did not release a detained Chinese fishing boat captain, Beijing on Thursday cut off exports of minerals to Japan that are used in such products as hybrid cars, according to a media report that was later denied by Chinese officials.