BEIJING (Reuters) - China said on Tuesday it opposed action by other countries under the pretext of freedom of navigation that undermined its sovereignty, after a U.S. aircraft carrier strike group began patrols in the contested South China Sea.

The U.S. navy said the strike group, including the Nimitz-class aircraft carrier the USS Carl Vinson, began "routine operations" in the South China Sea on Saturday amid growing tension with China over control of the disputed waterway.