FLORENCE, Italy (Reuters) - Former Italian prime minister Silvio Berlusconi is under investigation as part of an investigation into mafia bombings in 1993, a judicial source said on Tuesday, confirming newspaper reports. A mob boss jailed for the deadly attacks in Rome, Milan and Florence was recorded talking to his cellmate about the four-times premier, prompting a judge in Florence to reopen a shelved probe into Berlusconi s alleged involvement, the Italian newspapers Corriere della Sera and La Repubblica reported.  Berlusconi s lawyer Nicolo Ghedini said a previous investigation had shown his client was not involved in the bombings, which killed 10 people. Ghedini said the case had re-emerged for political reasons ahead of an important regional ballot in Sicily on Sunday and a national election due by next May.  Even speculating that (Berlusconi) could have been in any way involved in the events in question is so absurd as to make any comment unnecessary,  Ghedini said in a statement.  (It is) obvious that the umpteenth investigation can only end in a swift dismissal, as happened in the past.  A previous probe into the 81-year-old media mogul s alleged involvement in the case was shelved in 2011. Berlusconi was due to visit Sicily later on Tuesday to campaign for his Forza Italia (Go Italy!) party ahead of Sunday s regional election. Judges investigating the mafia case, which is raking over arguably the murkiest years in modern Italian history, heard fragmented recordings of conversations mob leader Giuseppe Graviano had last April in jail, the newspapers reported.   1992 he already wanted to get involved (in politics) ... and he wanted everything,  Graviano was reportedly recorded saying, referring to  Berlusca  - a common nickname for Berlusconi.   Berlusca ... asked me this favor ... I was convinced Berlusconi would win the election ... in Sicily ... he wanted to get involved ... but at that time the old guys were around ... he told me we needed a really good thing.  The mafia bombing campaign on mainland Italy stunned the country and helped lead to the collapse of the old political parties, which were riddled with corruption. Berlusconi entered politics in early 1994 and immediately won a national election. Forza Italia said in a statement that 1,296 mafiosi had been arrested during Berlusconi s years in office between 2001-05 and 2008-2011, including 32 of Italy s most wanted mobsters.  It said Berlusconi s administration had toughened prison conditions for mobsters and had seized 25 billion euros ($29.09 billion) of mafia property in its last three years in office. ($1 = 0.8595 euros) 