A rigid packet of smoking articles, comprising: a parallelepiped-shaped container having a front wall, a rear wall, a bottom wall, and two lateral walls; at least one inner package which encloses a group of smoking articles, is housed inside the container, has a smaller cross dimension with respect to the cross dimension of the container; a lid hinged to the container to close an open top end of the container; and a collar arranged inside the container so as to project partly outwards of the open top end, and which has: a first lateral wall resting on a corresponding lateral wall of the container; a front wall resting on the front wall of the container and having a U-shaped top recess that is arranged outside of the container; and a second lateral wall opposite the first lateral wall of the collar and resting on a corresponding lateral wall of the container; wherein the collar comprises at least one intermediate partition wall extending perpendicularly from the front wall of the collar, and which divides the inner volume of the container into only one open-topped main chamber housing the inner package, and into only one open-topped secondary chamber side by side with the main chamber; and wherein the intermediate partition wall (17, 21) initially forms part of the front wall of the collar and possibly of a lateral wall (13, 16) of the collar, is separated from the front wall of the collar by at least one U-shaped incision (38; 40), is connected to the front wall of the collar by means of a pre-weakened fold line joining one with the other the two opposite ends of the U-shaped incision, and is folded 90° with respect to the front wall of the collar; the packet of smoking articles being characterized in that: two intermediate partition walls (17, 21) which are mirrored and identical to each other and are arranged one over the other at different heights; and one intermediate partition wall (17, 21) extends on the left of the relevant pre-weakened fold line while the other intermediate partition wall (17, 21) extends on the right of the relevant pre-weakened fold line. a parallelepiped-shaped container having a front wall, a rear wall, a bottom wall, and two lateral walls; at least one inner package which encloses a group of smoking articles, is housed inside the container, has a smaller cross dimension with respect to the cross dimension of the container; a lid hinged to the container to close an open top end of the container; and a collar arranged inside the container so as to project partly outwards of the open top end, and which has: a first lateral wall resting on a corresponding lateral wall of the container; a front wall resting on the front wall of the container and having a U-shaped top recess that is arranged outside of the container; and a second lateral wall opposite the first lateral wall of the collar and resting on a corresponding lateral wall of the container; wherein the collar comprises at least one intermediate partition wall extending perpendicularly from the front wall of the collar, and which divides the inner volume of the container into only one open-topped main chamber housing the inner package, and into only one open-topped secondary chamber side by side with the main chamber; and wherein the intermediate partition wall (17, 21) initially forms part of the front wall of the collar and possibly of a lateral wall (13, 16) of the collar, is separated from the front wall of the collar by at least one U-shaped incision (38; 40), is connected to the front wall of the collar by means of a pre-weakened fold line joining one with the other the two opposite ends of the U-shaped incision, and is folded 90° with respect to the front wall of the collar; the packet of smoking articles being characterized in that: two intermediate partition walls (17, 21) which are mirrored and identical to each other and are arranged one over the other at different heights; and one intermediate partition wall (17, 21) extends on the left of the relevant pre-weakened fold line while the other intermediate partition wall (17, 21) extends on the right of the relevant pre-weakened fold line. two intermediate partition walls (17, 21) which are mirrored and identical to each other and are arranged one over the other at different heights; and one intermediate partition wall (17, 21) extends on the left of the relevant pre-weakened fold line while the other intermediate partition wall (17, 21) extends on the right of the relevant pre-weakened fold line.