According to Chino Gaston of 24 Oras, at least 30 Chinese maritime militia vessels were around Rozul or Iroquois Reef on Sunday.
Ray Powell a security analyst discovered the ships using satellite imagery and published the discovery on social media.
The militia vessels, which did not appear to be fishing, are being monitored by the Philippine Navy and Coast Guard.
The PCG said that its patrolling BRP Datu Pagbuaya issued radio challenges to the militia vessels, but no one responded.