Argentine President Cristina Fernandez has rejected accusations against her by a prosecutor who was mysteriously killed before giving potentially explosive testimony, calling on Monday for a deep reform of the intelligence services.

The prosecutor, Alberto Nisman, 51, was found dead at his home in the capital with a gunshot wound in his head on Jan 18. Just hours later he had been due to attend a congressional hearing to accuse Fernandez of obstructing his investigation into a 1994 bombing at a Jewish charities federation office.

Government officials said Nisman's allegations that Fernandez had reached a secret deal with Iran in exchange for economic benefits were absurd. Even so, the country's intelligence agency, overseen by her, has been plunged into suspicion that rogue agents were behind the prosecutor's mysterious death.