Security seal comprising: a seal body and an elongated member having a first end fixed to the body and a second free end, said body being formed there through with a passage for the free end of the elongated element and locking means associated with the passage to prevent withdrawal of the elongated element once introduced through the passage; and a separate outer cover that has one open end adapted to receive the seal body through said open end in its interior, the opposite end of the cover preventing removal of the seal body therethrough; characterized by further comprising: first locking means (16a, 16b) provided in the interior of said cover, said first locking means (16a, 16b) being in a region not occupied by the seal body when this latter is received within the cover; and a separate identification element (3; 19) adapted to be received through said open end of the cover in the said region not occupied by the seal body, which is provided with second locking means (14a, 14b) cooperable with said first locking means (16a, 16b) so as to prevent removal of the identification element (3; 19) after locking by insertion in the cover, wherein: said identification element (3; 19) is provided with an identification region adapted to receive identification means (18; 20) and is configured such that, in its locked position, it prevents withdrawal of the seal body through the said open end of the cover, said identification means (18; 20) being identifiable from outside said cover when said identification element is in the locked position. a seal body and an elongated member having a first end fixed to the body and a second free end, said body being formed there through with a passage for the free end of the elongated element and locking means associated with the passage to prevent withdrawal of the elongated element once introduced through the passage; and a separate outer cover that has one open end adapted to receive the seal body through said open end in its interior, the opposite end of the cover preventing removal of the seal body therethrough; characterized by further comprising: first locking means (16a, 16b) provided in the interior of said cover, said first locking means (16a, 16b) being in a region not occupied by the seal body when this latter is received within the cover; and a separate identification element (3; 19) adapted to be received through said open end of the cover in the said region not occupied by the seal body, which is provided with second locking means (14a, 14b) cooperable with said first locking means (16a, 16b) so as to prevent removal of the identification element (3; 19) after locking by insertion in the cover, wherein: first locking means (16a, 16b) provided in the interior of said cover, said first locking means (16a, 16b) being in a region not occupied by the seal body when this latter is received within the cover; and a separate identification element (3; 19) adapted to be received through said open end of the cover in the said region not occupied by the seal body, which is provided with second locking means (14a, 14b) cooperable with said first locking means (16a, 16b) so as to prevent removal of the identification element (3; 19) after locking by insertion in the cover, wherein: said identification element (3; 19) is provided with an identification region adapted to receive identification means (18; 20) and is configured such that, in its locked position, it prevents withdrawal of the seal body through the said open end of the cover, said identification means (18; 20) being identifiable from outside said cover when said identification element is in the locked position.