Diplomatic tensions between China and Japan escalated yesterday when Beijing called in Japan's ambassador for a second time after a Chinese fishing boat collided with two Japanese patrol vessels near a chain of disputed islands.

Tokyo has arrested the boat's captain. A Chinese Foreign Ministry statement said Japanese Ambassador Uichiro Niwa was summoned Wednesday to see Assistant Foreign Minister Hu Zhengyue, who demanded that the Chinese vessel be released immediately. The crew, who do not have passports, are waiting on the boat. Niwa also was summoned Tuesday evening.

But Japanese officials repeated their territorial claims over the islands, adding that they had no immediate plans to release the captain or the boat. Japan has also lodged a protest over the incident to the Chinese side.