MANILA — China is moving ships around disputed reefs in the South China Sea that could be used to reclaim land and build structures, President Benigno S. Aquino III of the Philippines said on Thursday.

The statement by Mr. Aquino comes as China has been more aggressive in pushing its territorial claims in the South China Sea, having recently enraged Vietnam by placing an oil rig in disputed waters.

Philippine officials said the Chinese ships were photographed from the air near the Gaven and Calderon Reefs, two areas of the Spratly Islands, a part of the South China Sea that includes reefs and islets claimed by China, the Philippines and Vietnam.