Mr Vincent McKenna, a former member of the IRA, said yesterday he plans to hand over an M-16 automatic rifle in "a symbolic act to help the peace process".
Mr McKenna, who claims to have been an intelligence officer from 1980 to 1992, will "surrender" the weapon during a British television programme to be screened on New Year's Day.
He said he was given the weapon by the film production company.
Mr McKenna is one of the participants in a documentary, Killing Time: The Millennium Poem, based on Simon Armitage's 1,000-line verse written to mark the millennium.