The present invention relates to a packaging article comprising i) an envelope defining at least one cavity, the envelope comprising water-soluble or liposoluble fibres, ii) at least one anhydrous dye composition containing at least one oxidation dye; and iii) optionally at least one anhydrous oxidizing agent, preferably in powder form; it being understood that the dye composition ii) and the chemical oxidizing agent iii), when it is present, are in one of the cavities of the envelope i). Another subject of the invention is the use of the packaging article for dyeing keratin fibres, and a process for dyeing keratin fibres using the said article. The use of the packaging article makes it possible to obtain dye compositions having good dyeing properties, which are easy to apply and which make it possible to obtain powerful colouring of the hair.