"A US Navy P-8 Poseidon aircraft was tasked to investigate reported object sightings by the Chinese aircraft made at 33,000 ft," an AMSA spokeswoman said in an emailed response to Reuters.
"The objects were spotted by the Chinese aircraft as it was heading back to Perth. Drift modelling was undertaken on the sighting. The P-8 was unable to relocate the reported objects."
The Chinese Ilyushin IL-76 aircraft spotted two "relatively big" floating objects and several smaller white ones dispersed over several kilometers, the Xinhua news agency reported earlier.