The prosecutor of a U.N.-backed tribunal investigating the assassination of former Lebanese Prime Minister Rafik Hariri filed a new indictment Friday.

The new indictment, which includes "substantive new elements" that have only recently come to light, and the one it replaces remain sealed. Prosecution office spokeswoman Sophie Boutaud de la Combe refused to elaborate on the new details that prompted the update.

"Its content is confidential," she said. "Unfortunately, I can say no more."

Hariri was killed along with 22 others by a truck bomb on Beirut's Mediterranean seafront on Feb. 14, 2005.

The new indictment is expected to further delay a judge's decision on whether to confirm the indictment and issue arrest warrants for suspects.

The Special Tribunal for Lebanon issued a statement saying the "large volume of supporting material" must be carefully scrutinized by Belgian judge Daniel Fransen, who will decide whether to confirm or dismiss the indictment. He also has the option of rejecting some of the charges and confirming others.

"It is anticipated that this will be completed in the coming months," the statement said.

Canadian prosecutor Daniel Bellemare submitted his first indictment on Jan. 17 and expanded it for the first time on March 11. He has not ruled out further changes or new indictments.

"The amendment of an indictment or the filing of new indictments is and will continue to be guided solely by the evidence uncovered by the ongoing investigation," Bellemare said in a statement.

Members of Hezbollah, a Shiite militia backed by Iran, are expected to be named in the indictment.

Hezbollah denies any involvement in Hariri's slaying, and its leader, Sheik Hassan Nasrallah, has said his group would "cut off the hand" of anyone who tries to arrest any of its members.

Unlike other international courts, the Hariri tribunal can hold trials in absentia if suspects cannot be arrested.

Hezbollah forced the collapse of Lebanon's Western-backed government led by Saad Hariri — son of the slain former prime minister — in January in a dispute over the tribunal.

Hezbollah's favored candidate, Najib Mikati, was named Lebanon's new prime minister, but he has been unable to form a government. Saad Hariri, who is serving as a caretaker until a new government is formed, has said he is joining the opposition, signaling he will be a fierce opponent of Hezbollah.