a polyolefin graft polyamide composition incorporating lamellar nanofillers . also , a tube , pipe or analogous formed from a multilayer at least one of the layers of which contains this composition . a thermoplastic composition having a polyolefin backbone containing a residue of at least one unsaturated monomer and a plurality of polyamide grafts , and also another component , wherein : the polyamide grafts are attached to the polyolefin backbone by the residue of the unsaturated monomer comprising a function capable of reacting via a condensation reaction with a polyamide having at least one amine end group and / or at least one carboxylic acid end group , the residue of the unsaturated monomer is attached to the backbone by grafting or copolymerization , wherein the other component consists of platy nanofillers , said nanofillers being phyllosilicates and representing from 1 % to 6 . 5 % by weight of the composition .