Some 55 leading mafiosi were flown out from the main jail in Palermo in military planes during the night and sent to an island prison off Tuscany.
The move came hours after the Mafia blew up Judge Paolo Borsellino and five bodyguards with some 90lb of explosives hidden under a car.
The jailed mafiosi, used to a fairly relaxed life in Palermo, were moved to a top security section on the island of Pianosa, off Elba, for prisoners convicted of terrorism. Restoration work on the disused section began after the last Mafia outrage - the murder of Judge Giovanni Falcone, his wife and three bodyguards in May.
Other Mafia leaders were transferred to a top security jail on the mainland while 200 troops took up position at dawn around Palermo's Ucciardone jail where the Mafia men had been imprisoned. The Defence Ministry said the army would not be used to combat the Mafia, but that 800 soldiers would be deployed to guard jails and other sites in Sicily. An extra 530 paramilitary Carabinieri were also sent to the island.
There was unrest among the 400 policemen who act as bodyguards in Palermo. Overnight, an angry crowd that included many police bodyguards scuffled with paramilitary police outside the office of the Palermo civil governor.
One senior anti-Mafia investigator, who would not give his name, likened the motive for the murder of the two judges to the assassination of Colombian judges by drug barons. 'The Mafia has taken a 'Colombian' road to make the state yield and give up in exchange for Mafia peace,' he said.
In a statement on the bombing, Nicola Mancino, the Interior Minister, announced that the government would speed up the creation of an anti-Mafia force to spearhead the state's counterattack. 'I confirm that within the next few months we will have an effective anti-Mafia agency of 2,000-3,000 men,' Mr Mancino pledged.