Argentina’s former president Cristina Fernández de Kirchner has appeared in court, where she denied covering up for Iranians accused of involvement in a 1994 bombing at a Buenos Aires Jewish center that left 85 people dead.

Calling the case an “absurdity”, Kirchner, who held office from 2007 until 2015, went on to attack the judge overseeing the case, which is based on charges first levelled two years ago by a federal prosecutor who was found dead in his home shortly before he was due to present his allegations publicly.

“I don’t expect any justice from you,” Kirchner, reading from a 17-page prepared statement, told the federal judge Claudio Bonadío on Thursday.

Kirchner is facing accusations of treason and plotting a cover-up for signing a 2012 pact with Iran that would have allowed senior Iranian officials accused of the deadly attack to be investigated in their own country, rather than in Argentina.

The judge, whom Kirchner tried to remove from office while she was still president, has 15 days to rule on whether to press forward with the charges, which also apply to Kirchner’s former foreign minister, Héctor Timerman, and other political aides.

The hearing came after Sunday’s congressional elections, in which Kirchner won a senate seat despite a surge in support for the president, Mauricio Macri, the center-right leader who succeeded her in office.

Senators enjoy immunity from prosecution, although this week congress stripped a former minister in Kirchner’s government of his immunity as part of a corruption inquiry.

“This is a great judicial absurdity,” said Kirchner. “The aim of this judicial persecution is to intimidate opposition leaders in congress. They want a submissive congress.”

The charges of the federal prosecutor Alberto Nisman – who was found dead in his apartment with a bullet wound to the head just one day before he was to appear before congress to set out his case – had been rejected several times by courts as lacking substance, but the case was reopened in February.

In asking for the case to be resumed, a federal prosecutor, Gerardo Pollicita, said that there existed “a criminal plan that had been orchestrated and put into practice” and whose aim was to “grant impunity” to Iranians who had international arrest warrants out on them.

The agreement was passed by the Argentinian congress but not by Iran, and never came into effect.

The former head of state said in court that the memorandum “had one aim: to allow an investigation into the Iranians accused in the AMIA attack, so that the case could move forwards”.

She has argued in the past that since Iran and Argentina have no extradition agreement, and Argentina does not carry out trials in absentia, there was no other way to proceed with the investigation.

Prosecutors are also looking into whether the country’s leadership at the time of the attack on the AMIA Jewish center had conspired to obstruct the investigation.

In the dock are the ex-president Carlos Menem, who ran the country from 1989 to 1999, the judge who led the investigation for its first 10 years, the ex-head of the intelligence agency, two prosecutors and a representative of the Jewish community, among others.

The AMIA bombing was the most deadly attack ever carried out in Argentina, and occurred just two years after a bomb attack on the Israeli embassy in Buenos Aires.

• This article was amended on 31 October 2017. An earlier version said that “judges stripped a former minister in Kirchner’s government of his immunity as part of a corruption inquiry”. It was congress which took this action.

