An Argentinian prosecutor asked a judge on Wednesday to block a joint investigation by the Argentinian and Iranian governments into the 1994 bombing of a Buenos Aires Jewish center.

Alberto Nisman’s appeal asked the court to declare the so-called “truth commission” agreement between the two countries unconstitutional, Reuters reported. The commission has been tasked with probing the deadly attack that killed 85 people, and for which Israel blames Iran and Hezbollah.

Nisman claimed the agreement violates constitutional rights such as judicial independence, the guarantee of due process, and the right of justice for victims.

The accord with Tehran, finalized in May 2013, promises to enable Argentinian prosecutors to travel to Iran and question high-ranking officials suspected of organizing the attack. But there is no indication that Iran will ever allow the suspects to be extradited. In 2007, Interpol issued arrest warrants for five Iranians and one Lebanese person in connection to the bombing, and at Argentina’s request, according to Reuters.

Argentina and Israel have long suspected Iranian involvement in the 1994 attack, but Buenos Aires rejected Jerusalem’s dismay when plans to form the commission first came to light in January.

“The attack against the people of our country on July 18, 1994 did not involve any Israeli citizens. Victims were mostly Argentines and included six Bolivians, two Poles and one Chilean,” read an Argentinian foreign ministry statement at the time. “It should be noted that Argentina has never demanded of an Israeli ambassador to provide explanation for his government’s actions.”

The agreement also angered Argentina’s Jewish community and in April AMIA and the national Jewish political umbrella group DAIA filed a joint petition with the Federal Administrative Court arguing that Argentina’s Congress acted unconstitutionally in voting to support the joint commission.

Nisman had previously filed a 500-page indictment that accuses Iran and Hezbollah of establishing terror cells across South America. In particular, he named Mohsen Rabbani, a former Iranian cultural attache and presidential candidate, as the coordinator of Iranian clandestine activities on the continent.

Nisman also outlined Iran’s “dual use of diplomatic offices, cultural or charity associations and even mosques, as coverage to hide illegal activities.”

Iranian officials have rejected such charges as a Zionist conspiracy.