An arrest warrant was issued on Tuesday for a former top-ranking member of Italian military intelligence service SISMI in connection with an illicit bugging probe.
Ex-SISMI No.2 Marco Mancini is accused of corruption and disclosure of confidential information.
The former head of SISMI's counter-espionage operations is already in prison in connection with a separate investigation into the alleged CIA kidnapping in 2003 of a Milan-based Muslim cleric suspected of involvement in terrorism.
The bugging case erupted in September, when 21 people were arrested including officials at telecoms giant Telecom Italia and tyre group Pirelli, Telecom's parent company.
The probe sent shock waves through the political and business establishment when it initially appeared that the wiretapping ring had been gathering information on political, business and media figures as well as ordinary Italians, although it was not known for what ends and for whom.
The arrested included former Telecom security chief Luciano Tavaroli; Pirelli security chief Pierguido Tezzi; the owner of a Florence-based private investigation firm Polis d'Istinto, Manuele Cipriani; and several police officers.
Tavaroli and Cipriani, who are suspected of embezzling funds from Pirelli and Telcom to the tune of 20.7 million euros, were both served with fresh arrest warrants on Tuesday.
Tavaroli is already in jail while Cipriani is under house arrest following a brief stint in jail.
Mancini's lawyer Luca Lauri said the arrest warrant against his client was "completely unjustified".
He said that investigators had so far failed to question Mancini, denying him the chance to demonstrate his innocence.
Last month, the Justice Ministry eased fears that the bugging ring had amassed potentially damaging information on politicians, businessmen and celebrities.
Justice Undersecretary Luigi Li Gotti said that the ring had only collected lists of the calls made by the people it spied on, and not their contents.
The government had initially passed an emergency decree ordering the destruction of all the information gathered by the ring in order to protect the privacy of the spy victims.
The decree included heavy fines for publishing the contents of illegally taped conversations.
But Li Gotti said that prosecutors had confirmed that there was no information to destroy.
"There is no material to eliminate because there was no actual eavesdropping. There are only lists of calls and that's it, without the contents of the calls," he said.
When asked why there had been a press-fuelled scandal and the approval of an emergency decree, Li Gotti said: "The media revealed the names of the people who appeared on the call lists. Parliament then agreed on the need for a decree because it feared the existence of information that had been illicitly gathered".
Li Gotti stressed that the bugging ring was in fact under investigation for suspected corruption, fraud and revealing confidential information and not illicit wiretapping.
