CHINA warned yesterday that it was “extremely concerned” about a suggestion from a US commander that ships and aircraft should challenge China’s claims in the South China Sea by patrolling artificial islands it has built.

China’s action to back up its sovereignty claims in the South China Sea have included land reclamation and the construction of ports and air facilities on several reefs in the Spratly Islands.

The work has rattled China’s neighbours, in particular US ally the Philippines.

US Pacific forces commander Admiral Harry Harris told a Senate hearing on Thursday that China’s building of three airfields on small islands was of “great concern militarily.”

Chinese Foreign Ministry spokesman Hong Lei warned that China was “extremely concerned” about the comments.