President Rodrigo Duterte said on Friday he wants to ask China if it is building again in the South China Sea after receiving an intelligence report barges were spotted in the disputed waters.

In a speech during the inauguration of the Davao International Container Terminal in Davao del Norte, Duterte said he got a report from the Philippine Coast Guard, which made some trips in the area.

"We have just read the intelligence report last night and there seems to be new barges coming in and they suspect there's going to be another construction somewhere," he said, noting that barges are used "to put something there and bring it somewhere."

Duterte in an interview after the speech, said when he has a chance to talk with Chinese Ambassador to the Philippines Zhao Jianhua, he would ask: "Is there any ongoing construction or expansion in the South China Sea?"

He would also ask if "we can still have the fishing rights which is really the entitlement of our country having won the arbitral proceeding (in the South China Sea)?."

China has reclaimed some reefs in the South China Sea, which the Permanent Court of Arbitration said has caused huge damage to the marine environment.

Duterte raised concern if China would continue with its activities in the area, which is considered as the "safest, cheapest and shortest" sea lane could be a "source of conflict, thereby, the threat is always there."

He said the cost of trade and even insurance might increase.

On July 12, PCA made an award to the Philippines on its petition against China's nine-dash line.

Duterte said he would not raise the South China Sea issue when he attends the Association of Southeast Asian Nations in Laos next week.

But he reassured he would bring up the matter once bilateral talks with Chinese leaders takes place.

"I said there will be a time I will say, 'this is the arbitral ruling and if you want to talk to me, this will be my platform and we do not go out of the four corners of the document," he said. Celerina Monte/DMS