A safety plug for use in rock drilling operations. The safety plug includes a base part and one or more expander elements. The base part has a leading end and a trailing end and a generally cylindrical outer surface between the leading and trailing ends, on which one or more external spirals are formed. The external spirals are provided to engage the internal wall of a bore within which the safety plug is inserted to anchor the base part within the bore. The one or more expander elements have an inactive non-expanded condition and an active, laterally expanded condition. The safety plug is operable to absorb load applied to its leading end in two stages, whereby: in a first stage, load applied to the leading end of the one or more expander elements up to a predetermined load is transferred to the base part and the base part is operable to react the load by engagement of the spirals with the internal wall of the bore. In a second stage, load applied to the same leading end beyond the predetermined load causes the one or more expander elements to transition to the active condition in which the expander elements expand laterally to engage the internal wall of the bore to resist shifting movement of the safety plug within the bore in the direction of the applied load.