An Argentine special prosecutor who accused President Cristina Fernandez of orchestrating a cover-up in the investigation of Iran over the 1994 bombing of a Jewish community centre, has been found dead in his apartment, authorities say.

Alberto Nisman, who had been investigating the blast at the AMIA Jewish community centre in Buenos Aires that killed 85 people, said last Wednesday that Fernandez had opened a secret back channel to a group of Iranians suspected of planting the bomb.

He had said the scheme intended to clear the suspects so that Argentina could start swapping grains for much-needed oil from Iran, which denies any connection with the bombing.

"Alberto Nisman was found dead on Sunday night in his flat on the 13th floor of the tower Le Parc, in the Buenos Aires district of Puerto Madero," Argentina's Security Ministry said in a statement.

The ministry said Nisman's security guards had alerted his mother on Sunday afternoon that he was not answering his front door or phone, and the Sunday papers were still on his doorstep.

Nisman's mother found the door to his apartment locked from the inside and got a locksmith to open it. She found her son's body on the floor of the bathroom, and called the police.

"Next to Nisman's body ... a 22-calibre handgun was found, together with a bullet casing," the Security Ministry statement said.

Closed-door hearing

Nisman, who local media said was 51, had been due to take part in a closed-door hearing in parliament on Monday to explain his accusations against Fernandez.

"Everything indicates it was a suicide," Sergio Berni, secretary of national security, told local television. "We have to see if gunpowder is found on his hands."

By mid-morning the autopsy had begun, with the official cause of death expected to be announced over the days ahead.

"He was alone in the apartment," Viviana Fein, prosecutor, said. "There are no witnesses."

Al Jazeera's Andrew Simmons, reporting from Buenos Aires, said there is a political crisis in the country, with many asking whether Nisman was murdered or committed suicide.

The Clarin daily reported just a few days earlier that Nisman had said: "I could end up dead because of this."

Nisman, in a separate TV interview, had also been considering increasing his security detail.

Israel's Foreign Ministry issued a statement mourning Nisman's death and urging Argentine authorities to carry on his work.

Source: Al Jazeera and agencies