Method for producing a fuel tank provided with internal accessories (2, 3) and having a wall (1) made of plastic made in a single piece by moulding a split parison or a parison in at least two parts, said method comprising the following steps: a) the parison is introduced in the heat-softened state into a mould comprising dies; b) a core on which the accessories (2, 3) are placed is introduced inside the parison; c) the parison is pressed onto the dies of the mould; d) the accessories (2, 3) are fastened to the parison with the aid of the core in an ideal layout; e) the core is withdrawn and the mould is closed; f) the tank is moulded from the parison; and g) the tank is removed from the mould.