But the man, who presented himself as a member of the powerful Hezbollah militia, denied all responsibility for the 2005 killing, saying, "I am innocent of all charges against me."
Four members of the radical Syrian-backed Hezbollah movement have been indicted for the massive 2005 car bomb attack that killed Rafiq Hariri while his convoy was passing a Beirut hotel.
Prosecutors have indicted Salim Ayyash, 47, Mustafa Badreddine, 50, Hussein Anaissi, 37 and Assad Sabra, 34, for the murder.
In Lebanon, Prosecutor General Said Mirza has "categorically denied that the prosecution or the police are aware of the place of residence of any of the four suspects and have not proceeded with the arrests," according to a statement from Justice Minister Shakib Qortbawi.
The prosecutor "informed the minister that he would pursue legal measures to ascertain the true identity of the person to whom these remarks were attributed," the statement said.
Hezbollah officials were not immediately reachable for comment. The Shiite party's media did not mention the interview.
Ayyash and Badreddine face five charges including that of "committing a terrorist act by means of an explosive device" and homicide, while Anaissi and Sabra face charges of conspiring to commit the same acts.
The whereabouts of the four are currently unknown, with the UN-backed tribunal's president last Thursday calling for greater efforts to arrest the men.
The tribunal said Wednesday it had enough evidence to try them.