U.S. military forces will continue to operate in the South China Sea in accordance with international law, the U.S. Chief of Naval Operations John Richardson said on Wednesday during a visit to a Chinese naval base.

China has refused to recognize a ruling by an arbitration court in The Hague that invalidated its vast territorial claims in the South China Sea and did not take part in the proceedings brought by the Philippines.

China has repeatedly blamed the United States for stirring up trouble in the South China Sea, a strategic waterway through which more than $5 trillion of trade moves annually.

China, Brunei, Malaysia, the Philippines, Taiwan and Vietnam all have rival claims, of which China's is the largest.

The United States has conducted freedom of navigation patrols close to Chinese-held islands, to Beijing's anger, while China has been bolstering its military presence there.

Meeting Yuan Yubai, commander of the Chinese North Sea Fleet, Richardson "underscored the importance of lawful and safe operations in the South China and elsewhere professional navies operate", the U.S. Navy said.

U.S. forces would keep sailing, flying and operating wherever international law allows, Richardson added.

"The U.S. Navy will continue to conduct routine and lawful operations around the world, including in the South China Sea, in order to protect the rights, freedoms and lawful uses of sea and airspace guaranteed to all. This will not change."

Richardson said he was supporting of the deepening of relations between the two navies.

"But I will be continuously reassessing my support conditioned on continued safe and professional interactions at sea. In this area we must judge each other by our deeds and actions, not just by our words," he added.

The United States has complained that Chinese aircraft and ships have performed "unsafe" maneuvers while shadowing U.S. ships and planes, particularly in the South China Sea.

Speaking in Sydney on Wednesday, U.S. Vice President Joe Biden assured key ally Australia there would be no retreat from Washington's pivot to the Asia-Pacific region, regardless of who wins November's presidential election.