A prosecutor investigating a 1994 bomb attack, one of the worst in Argentina's history, has accused President Cristina Fernandez of secretly negotiating with Iran to avoid punishing those responsible.

The bombing of the Argentine-Israeli Mutual Association in Buenos Aires remains unsolved, but Argentina and Iran reached an agreement in 2013 to investigate the attack that killed 85 people and wounded 200.

Argentine prosecutor Alberto Nisman in 2013 released an indictment accusing Iran and Hezbollah of organising the blast. Iran denies any involvement.

Nisman on Wednesday accused Fernandez and other senior Argentine officials of agreeing not to punish at least two former Iranian officials in the case.

He asked a judge to call in Fernandez and others, including Foreign Minister Hector Timerman, for questioning.

"The president and her foreign minister took the criminal decision to fabricate Iran's innocence to save Argentina's commercial, political and geopolitical interests," Nisman said.

A federal judge must now decide whether to hear the complaint and whether anyone should be summoned for questioning.

'Foolishness'

Government officials criticised the prosecutor's decision, calling it ludicrous.

"This is rarely seen foolishness," Anibal Fernandez, the presidency's secretary-general, told local media.

The prosecutor said Timerman struck "secret deals with Tehran" to set up false trails and alter the investigation to exonerate at least six of the Iranians from any responsibility.

Speaking to reporters, Nisman said that "the impunity of the Iranians was ordered by the president and instrumented by Timerman" with the goal of scoring closer geopolitical ties with Iran, trading oil and even selling weapons.

A joint Argentina-Iran truth commission has been fiercely defended by Fernandez's government as the best means of resolving a case that has moved forward only in fits and starts in Argentina's judiciary and been frustrated all along the way by Iran's refusal to cooperate.

But the probe has not advanced and the victims' relatives believe the agreement has protected the perpetrators.

Mohsen Rabbani, Iran's former cultural attache in Buenos Aires, and the Islamic republic's former intelligence minister, Ali Fallahian, are among the suspects in the July 18, 1994, attack.

The prosecutor has tried for years to get Rabbani and other suspects extradited to face trial in Argentina.