Argentine President Cristina Kirchner on Sunday announced an agreement with Iran to create an independent commission to investigate the deadly 1994 bombing of a Jewish center in Buenos Aires.
Iran confirmed the deal.
Argentina has long accused Iran of masterminding the deadly attack and has since 2006 sought the extradition of eight Iranians, including current Defense Minister Ahmad Vahidi and former president Akbar Hashemi Rafsanjani.
Iran has always denied any involvement in the bombing, in which 85 people died, and has refused to arrest the suspects.
Kirchner said the two sides had agreed to create a "truth commission" with five independent judges -- none of whom can come from either Iran or Argentina.
She said the agreement may allow Argentine authorities to finally question those for whom Interpol has issued "red notices", which alert the international community of arrest warrants.
Kirchner called the agreement "historic," saying "it guarantees the right to due process of law, a fundamental principle of international criminal law."
The agreement, signed by Argentina's foreign minister and Iranian authorities in Addis Ababa on the sidelines of an African Union summit, must still be ratified by lawmakers in both countries.
The Iranian foreign ministry published pictures of the signing ceremony, media in Tehran reported.
The reports said Iran and Argentina agreed to "close that file through mutual cooperation and with the help of independent lawyers" in order to "shed light on this issue."
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Argentine Foreign Minister Hector Timerman said the agreement contains "no secret clauses," and that under its terms, Iran "will deliver all its documents" on the bombing to judicial authorities.
The accord comes after several months of negotiations -- starting in October at the United Nations in Geneva -- aimed at resolving the pending legal actions.
The two countries' foreign ministers have also met several times in Zurich, including most recently in early January, for talks Iran termed "very constructive."
The discussions have drawn criticism from both Israel and Argentina's 300,000-strong Jewish community, the largest in Latin America.
Both have demanded there be no let-up in Argentine authorities' efforts to put the Iranian suspects on trial.
Argentina's foreign minister will meet Tuesday in Buenos Aires with relatives of the victims, some of whom expressed negative reactions to the news, though the two top Argentine Jewish groups did not immediately comment.
The agreement "is a monumental step backward against the decision of Argentine justice," said Luis Czyzewski, father of Paola, who died in the bombing.
Another, Sergio Burstein, who heads an association of friends and relatives of victims, said simply, "it was a shock."
The July 18, 1994 bombing occurred when a van loaded with explosives blew up outside the Argentine Jewish Mutual Aid Association (AMIA), leveling the seven-floor building housing the charities federation.
It came two years after an attack on the Israeli embassy in Buenos Aires that killed 29 people and wounded 200.
Buenos Aires has long accused Tehran of being behind both attacks, charges denied by the Islamic republic.