The Air Accidents Investigation Branch says video footage of the submerged wreckage of Emiliano Sala's plane shows "one occupant is visible".
The AAIB has issued a brief statement after the plane was found on the seabed on Sunday.
A privately-funded underwater search vessel FPV Morven located the missing Piper Malibu plan within hours of launching alongside an AAIB-commissioned Geo Ocean III team on Sunday.
The plane disappeared from radar over the Channel Islands a fortnight ago with 28 year old footballer Emiliano Sala and pilot David Ibbotson (59) on board.
"Early in the search, the Morven identified an object of interest on the seabed using its side-scan sonar equipment. It cleared the immediate area for the Geo Ocean III to use its underwater remotely operated vehicle (ROV) to survey the area of the seabed in which the object was located. Based on analysis of ROV video footage, the AAIB investigators on board the vessel concluded that the object is wreckage from the missing Piper Malibu aircraft, registration N264DB.
The ROV carried out a further search of the area overnight, but did not identify any additional pieces of wreckage.
Tragically, in video footage from the ROV, one occupant is visible amidst the wreckage. The AAIB is now considering the next steps, in consultation with the families of the pilot and passenger, and the police."
The AAIB will publish a report into the accident within the month and says it will not be commenting until then.