At the previous hearing Riina had informally said via his lawyer, Giovanni Anania, that he would testify.
"I'm ill. I have a problem," Riina, 86, said in a video link from Parma prison.
It would have been the first time Riina had testified in court.
Other defendants in the case include informants such as Giovanni Brusca; the son of a Mafioso Palermo mayor, Massimo Ciancimino; ex-Berlusconi aide Marcello Dell'Utri; former interior minister Nicola Mancino and ex-Carabinieri special force officers.
Former prosecutor Antonino Ingroia said recently he is writing a novel on his time at the trial on alleged talks between the State and the Mafia to stop the bombs, and suggested he would reveal the contents of wiretaps, later destroyed, between former President Giorgio Napolitano and former interior minister and Senate Speaker Mancino.
"There are things to be told," he said.
Mancino is among several people on trial for the alleged talks to stop bombings that included the murders of anti-Mafia magistrates Giovanni Falcone and Paolo Borsellino in 1992.
Napolitano gave evidence in the trial but taped conversations between him and Mancino were ordered destroyed.
With ANSA
