A method of fabricating fire repellent cigarette paper for a heat-not-burn aerosol generating article is disclosed, the method (100, 300) comprising the steps of: grinding (105, 305) plant material to produce ground fibres; applying (115, 315) a treatment solution to the ground fibres, the treatment solution comprising a donor of a phosphorous group, to provide treated fibres comprising a phosphorous group; creating (135, 325) a paper pulp comprising the treated fibres and water; and inputting the paper pulp into a paper machine to form a fire repellent cigarette paper comprising 0.1% to 10% of phosphorous groups by weight of the total weight of the fire repellent cigarette paper.