By Junko Ogura and Jethro Mullen, CNN

updated 7:03 AM EDT, Fri September 14, 2012

STORY HIGHLIGHTS

Tokyo (CNN) -- Six Chinese maritime surveillance ships briefly entered waters around a group of islands at the center of a heated territorial dispute between Tokyo and Beijing, ignoring warnings from the Japanese authorities amid escalating tensions in the region.

The Chinese ships arrived near the uninhabited islands -- which Japan calls Senkaku and China calls Diaoyu -- on Friday morning and began patrols and "law enforcement," China's state-run news agency Xinhua reported.

The islands, situated in the East China Sea between Okinawa and Taiwan, are currently under Japanese control, but China claims they have been an "inherent" part of its territory "since ancient times." The long-running argument over who has sovereignty has resulted in occasionally violent acts of public protest.

The United States,a key ally of Japan, has repeatedly urged Tokyo and Beijing to resolve the dispute through dialogue. U.S. Defense Secretary Leon Panetta will meet with his counterparts in Japan and China during a visit to the region that begins this weekend, the Department of Defense said Thursday.

The Chinese ships entered Japanese territorial waters Friday despite warnings from the Japanese Coast Guard, said Shinichi Gega, a spokesman for Japan's 11th Regional Coast Guard Headquarters.

The vessels had all left the waters by mid-afternoon and headed north, the Japanese Coast Guard said later Friday, noting that sea in the area was getting rough as a huge storm, Super Typhoon Sanba, approached from the south.

Japanese Chief Cabinet Secretary Osamu Fujimura said Japan would intensify its own patrols of the area in response to what he described as an "unprecedented scale of invasion" of Japanese waters.

Originally posted here:

Chinese ships carry out patrols around islands at center of dispute with Japan