The footballer and pilot's plane disappeared on 21 January.
Two seat cushions have been found which are likely to have come from the missing aircraft which was carrying Cardiff City footballer Emiliano Sala.
The Air Accidents Investigation Branch said in a statement: "On the morning of Monday, January 28, we were advised by the Bureau d'Enquetes and d'Analyses, the French safety investigation authority, that part of a seat cushion had been found on a beach near Surtainville on the Cotentin Peninsula.
"A second cushion was found in the same area later that day.
"From a preliminary examination, we have concluded that it is likely that the cushions are from the missing aircraft."
The AAIB will conduct an underwater search of four square miles for the missing plane, targeted on its known flight path and known radar positions.
The underwater seabed search of the area is expected to commence this weekend while a separate, privately funded search is being conducted in the area.
While the searches are separate, they're liaising with one another in their efforts.
Sala, along with pilot David Ibbotson, disappeared on 21 January while flying over the Channel Islands.
