The Iranian government and Lebanese militia group Hezbollah have been formally charged over the 1994 bombing of a Jewish centre in Buenos Aires.
The blast was the worst terror attack in Argentina's history
Argentine prosecutors are calling for the arrest of former Iranian President Hashemi Rafsanjani and seven others.
Chief prosecutor Alberto Nisman accused the Iranian authorities of directing Hezbollah to carry out the attack.
Hezbollah and Iran both deny that they were involved in the blast, which killed 85 and wounded 300.
The blast, on 18 July 1994, reduced the seven-storey Jewish-Argentine Mutual Association (AMIA) community centre in Buenos Aires to rubble.
Nobody has ever been convicted of the attack, but the current government has said it is determined to secure justice.
Over the years, the case has been marked by rumours of cover-ups and accusations of incompetence, but little in the way of hard evidence.
Minor figures, including a policeman who sold the van used in the attack, have been named, but no-one has been convicted.
Local Jewish groups have long said the bombing bore the hallmarks of Iranian-backed Islamic militants.
Iran has repeatedly and vehemently denied any involvement in the attack.
Last November, an Argentine prosecutor said a member of Hezbollah was behind the attack and had been identified in a joint operation by Argentine intelligence and the FBI.
But Hezbollah said that the man, Ibrahim Hussein Berro, had died in southern Lebanon while fighting Israel.
The 1992 bombing of the Israeli embassy in Buenos Aires, which killed 29 people, also remains unsolved.