The Philippines and the United States are trying to verify a report Chinese coast guard ships have left a disputed shoal, allowing Filipino fishermen back to the rich fishing area that China seized in 2012, triggering tensions in the South China Sea.

Philippine Defence Secretary Delfin Lorenzana said the Philippine coast guard has reported Chinese ships have not been sighted at Scarborough Shoal in the last three days, but he added the report has to be validated.

Lorenzana said the Philippine air force plans to conduct aerial surveillance of the shoal off the northwestern Philippines as early as Saturday to check the situation.

A Chinese Coast Guard ship follows the Motoryacht Isla after it was ordered to leave the Scarborough Shoal in the South China Sea, June 18, 2016. NYT

China took effective control of Scarborough in 2012, after a tense standoff with Philippine vessels. Since then, Chinese coast guard ships have been driving Filipino fishermen away from the area, while farther south in the Spratly Islands, China went on to construct seven man-made islands despite protests from other claimants.

US State Department spokesman Mark Toner said the US was still assessing reports Chinese boats have left Scarborough Shoal, and Filipinos have resumed fishing there.