SINGAPORE (Reuters) - The South China Sea does not belong to any one nation and the United States will continue to sail and fly wherever international law allows, U.S. Vice President Mike Pence said on Friday, in a challenge to China which claims the waterway.

The United States has conducted a series of "freedom of navigation" exercises in the contested South China Sea, angering China, which says the patrols threaten its sovereignty.

"The South China Sea doesn't belong to any one nation, and you can be sure: The United States will continue to sail and fly wherever international law allows and our national interests demand," Pence said.

China, Brunei, Malaysia, the Philippines, Vietnam and Taiwan, all have claims in the South China Sea, through which some $3 trillion of shipborne trade passes each year.

Pence on Thursday told leaders of Southeast Asian nations there was no place for "empire and aggression" in the Indo-Pacific region, a comment that could be interpreted as a reference to China's rise.

Speaking to a regional summit, Pence directly criticized China's action in the South China Sea, according to a transcript of his remarks.

"Let me be clear: China's militarization and territorial expansion in the South China Sea is illegal and dangerous. It threatens the sovereignty of many nations and endangers the prosperity of the world," he said.

In Beijing, Chinese Foreign Ministry spokeswoman Hua Chunying said no country, including the United States, had ever provided any evidence of problems with freedom of navigation or overflight in the South China Sea.

"May I trouble you to remind Mr Pence, that the United States has yet to ratify the United Nations Law of the Sea Convention (UNCLOS)," Hua told a daily news briefing.

"If the United States can at an early date ratify and abide by UNCLOS, then I think this will benefit even more the protection of peace and stability in the South China Sea area."

The 1982 convention defines how coastal states are allowed to establish sovereignty over territorial seas and exclusive economic zones. China has signed and ratified it.

Pence's comments follow a major speech in October in which he flagged a tougher U.S. approach toward China, accusing it of "malign" efforts to undermine U.S. President Donald Trump and reckless military actions in the South China Sea.

(Reporting by John Geddie; Additional reporting by Ben Blanchard in Beijing; Writing by Jack Kim; Editing by Michael Perry, Robert Birsel)