A resin binder composition for the production of a fiber preform comprising an amount of at least one polyarylether thermoplast resin component and an amount of at least one thermoset resin component in weight ratio 80/20-10/90, in substantial absence of a catalyst which is active at the prevailing preform production temperature, wherein the polyarylether thermoplast has number average molecular weight (Mn) in the range 2,000-20,000, and comprises ether linked phenyl units and ether linked arylsulphone units and reactive end groups, method for producing a fiber preform using the thermally stable binder resin composition, a perform obtained with use of the method and composition, a method for injecting or infusing the preform with curable matrix resin, the curable injected or infused preform resin, a method for curing thereof and a cured composite obtained with the method.