BEIJING - China has rejected charges by the United States that it had "expanded its outposts in the South China Sea", saying its activities in its own territory were legitimate and justified.

Media reports Thursday quoted the US intelligence chief James Clapper as saying China was expanding its outposts in the South China Sea to include stations for ships and potential airfields as part of its "aggressive" effort to exert sovereignty.

"China has shown restraint and a responsible attitude in the South China Sea. Outsiders have no right to make groundless accusations," Foreign Ministry spokesperson Hong Lei said at a daily news briefing Friday.

He urged the United States to honor its commitments, to be prudent with its words and actions, and do more to contribute to China-US relations and regional peace and stability.