(57) Self adhesive tapes and labels especially suitable for security purposes comprise by way of example a conventional release layer 1 whereby the tape may be rolled into or unrolled from a spiral form, an ink layer 2 visible under ultraviolet light, applied as an expanse of ink, a pattern or one or more alphanumeric characters or other markings; a support substrate 3 typically consisting of UPVC, a conventional primer layer 4, and a conventional pressure-sensitive adhesive layer 5. As an alternative the ink which is visible under ultraviolet light can be printed upon the under surface of the substrate provided that this is transparent. Such tapes or labels can be used for packaging or labelling as a security feature which is visible under ultraviolet light but not otherwise visible.