The Philippines will conduct an "inquiry" on a reported missile launch by China in the South China Sea.

"We have no first hand knowledge about this missile launch except this news report," Defense Secretary Delfin Lorenzana said on Wednesday.

"We will conduct our own inquiry and will decide later what to do if proven correct," he added.

A report from Reuters, quoting a "US official, speaking on the condition of anonymity, said China tested multiple anti-ship ballistic missiles over the weekend."

The story quoted Pentagon spokesman Lieutenant Colonel Dave Eastburn as saying the United States was aware of the missile launched by the Chinese.

"Of course the Pentagon was aware of the Chinese missile launch from the man-made structures in the South China Sea near the Spratly Islands," Eastburn said.

The report said the Pentagon found the Chinese missile launch "disturbing and contrary to Chinese pledges that it would not militarize the disputed waterway." Robina Asido/DMS