Argentina’s foreign minister, Hector Timerman, on Tuesday quit his membership in a leading Jewish organization targeted by a deadly bombing in 1994, reports The Associated Press (AP).

Timerman announced his decision in a letter to the Argentine-Israeli Mutual Association (AMIA), criticizing its leaders for blocking a deal with Iran to jointly probe the country’s worst terrorist attack.

“I resign as member of an organization that we were once proud of but now puts us to shame,” Timerman was quoted as having said.

Former Iranian officials have been on an Interpol capture list for years, but Argentine prosecutors have never been able to question them. Timerman promoted the 2013 accord with Iran as a way to reach the truth behind the unsolved bombing.

AMIA and some other groups have criticized the deal, saying Tehran has failed to cooperate and turn over suspects in the bombing that killed 85 people.

The joint “truth commission” was approved by Congress but it has not been implemented because two Argentine courts ruled it unconstitutional, and it is now under review, noted AP.

Timerman made headlines recently in the saga revolving prosecutor Alberto Nisman, who accused Timerman and President Cristina Fernandez of helping shield the Iranian officials allegedly behind the bombing.

Nisman had drafted arrest warrants for Kirchner and Timerman, but was found dead on January 18, the day before he was to detail his allegations against the president to Congress.

Argentina’s justice system has dismissed Nisman’s accusations. Iran has denied any role in the attack.