Chinese and Japanese government ships exchanged warnings Friday in waters near disputed islands in the East China Sea, while Tokyo called on Beijing to protect its citizens amid anti-Japan protests and reported assaults in China.

Tensions between the Asian giants have flared anew after the Japanese government bought the islands from their private Japanese owners this week. The uninhabited islands, claimed by both countries as well as Taiwan, have become a rallying point for nationalists on both sides.

In response to Japan's purchase, China on Friday sent six surveillance ships into what Japan says are its territorial waters around the islands, called Senkaku by Japan and Diaoyu by China. Japanese coast guard ships radioed warnings to the Chinese vessels and two or three moved out of the territorial waters, said Yasuhiko Oku, a Japanese coast guard official.

Japan controls the islands, which are surrounded by rich fishing grounds and are near key shipping lanes, but China doesn't recognize those claims. State-controlled China Central Television repeatedly played footage of a Chinese Marine Surveillance officer aboard one of the ships radioing the Japanese vessels to demand they leave.

"The actions of your ships violate China's sovereignty and rights," the officer was shown saying. "Any unilateral act from your side regarding the Diaoyu islands and its affiliated islands is illegal and invalid. Please stop any infringing acts. Otherwise, your side will bear the consequences caused by your actions."

With a typhoon approaching the area, by Friday afternoon all six Chinese ships had left the 24-mile zone around the islands, said Yoshiyuki Terakado, another Japanese Coast Guard official.