(CNN) Seat cushions believed to be from the plane carrying missing footballer Emiliano Sala have been found, according to Britain's Air Accidents Investigation Branch (AAIB).

As a result, an underwater search, using side-scan sonar equipment, is expected to take place at the end of this week, covering four square nautical miles and taking up to three days.

The seat cushions were discovered by French authorities on a beach near Surtainville on the Cotentin Peninsula in the northwest coast of France.

In a statement released Wednesday, the AAIB said that after a preliminary examination it had concluded that it was "likely that the cushions are from the missing aircraft."

The aircraft carrying Cardiff City's record signing disappeared from radar last week near the Channel Islands.

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