MANILA (Reuters) — China should act responsibly in disputed territories in the South China Sea to avoid political and security issues, the skipper of the US Navy's seventh Fleet flagship said.

Southeast Asian states, including the Philippines, have become worried by China's increasingly aggressive stance on the complex set of disputes in the South China Sea.

"We expect them to be responsible on what they do as we are. And I believe if we act in that way, there should be no issues," Capt. Rudy Lupton, commander of the USS Blue Ridge, the command and control ship of the Seventh Fleet based in Japan.

Chinese naval forces recently carried out drills in the disputed southern waters amid tension with Washington over security in the Korean peninsula and South China Sea.

Last year, there was a collision between sonar equipment being towed by a US Navy warship and a Chinese submarine near Philippine waters. Lupton said the United States viewed the South China Sea as part of international waters, where global trade passes through freely, and everyone was entitled to operate in that area.

"We conduct operations here and China can operate in waters adjacent to China," Lupton told reporters after USS Blue Ridge docked at Manila's south harbour for a four-day visit. "Our president has said he doesn't view China as a threat."

The United States has urged the several states claiming dozens of atolls and islets, some believed to be holding valuable oil and mineral assets, to settle the disputes peacefully.