Panel suitable for assembling a waterproof floor or wall covering, method of producing a panel

A panel suitable for assembling a waterproof floor or wall covering by interconnecting a plurality of said panels with each other,

• wherein the panel has a substantially planar top surface, and a substantially planar bottom surface, at least four substantially linear side edges of which at least one pair of opposite side edges which are provided with interconnecting coupling means for interconnecting one panel within another, the panel having a sandwich structure which comprises a core layer composed of at least a thermoplastic material, a rigid top layer and a reinforcing layer situated in between the core layer and the top layer, said reinforcing layer being substantially made of at least one thermoplastic material, wherein the core layer is provided with at least a part of the interconnecting coupling means, wherein the panel has an overall rigidity between 35 and 45 N/mm2, and wherein the rigid top layer comprises at least two plies of cellulose-based layer and a cured resin.