China said on Thursday an American warship had illegally entered its territorial waters in the South China Sea and was expelled, which the United States denied in the latest salvoes over Beijing"s claims in the busy waterway. In a statement, the Chinese military"s Southern Theatre Command said the USS Curtis Wilbur entered the waters near the Paracel islands without permission, adding that its ships and planes followed the U.S. vessel out. It said the U.S. action violated China"s sovereignty and undermined regional peace and stability. However, the U.S. Navy"s 7th Fleet said the vessel "asserted navigational rights and freedoms" near the Paracel islands, over which China, Taiwan and Vietnam all claim sovereignty. The Chinese military"s comments were false, it added. "USS Curtis Wilbur was not "expelled" from any nation"s territory," it said. "USS Curtis Wilbur conducted this Freedom of Navigation Operation (FONOP) in accordance with international law and then continued on to conduct normal operations in international waters." The South China Sea has become one of many flashpoints in the testy relationship between China and the United States, with Washington rejecting what it calls unlawful territorial claims by Beijing in the resource-rich waters. U.S. warships have passed through the South China Sea with increasing frequency in recent years, in a show of force against the Chinese claims. On Tuesday, the USS Curtis Wilbur had sailed through the Taiwan Strait, angering China, which claims self-ruled Taiwan as its own territory. read more In a statement addressing both that incident and Thursday"s flare-up, China"s defence ministry described the U.S. warship"s movements as a serious provocation. "China"s military will take all necessary measures to deal with all threats and provocations," it added.