A Special Tribunal for Lebanon, set up by the United Nations to investigate the killing of former Lebanese prime minister Rafik al-Hariri, will begin work on Sunday.
Lebanese authorities are holding seven people, including four generals, in connection with the attack.
Registrar Robin Vincent said on Tuesday he expected the prosecutor to ask for them to be transferred to The Hague.
Prosecutor Daniel Bellemare has said the opening of the tribunal does not mean legal proceedings will start immediately and investigations will continue.
Mr Vincent said he expected the tribunal to complete its work in three to five years.
Mr Hariri and 22 other people were killed in a car bomb in Beirut on 14 February, 2005.
Syria was blamed by some for the bombing. Damascus denies this.