Rome, February 22 - The Rome prosecutor's office opened a probe on Friday into an election letter sent to millions of Italians signed by ex-premier Silvio Berlusconi about an IMU property-tax rebate. The probe was instigated by a candidate for the regional council in Lazio province, Gianfranco Mascia of the Civic Revolution Party founded by former anti-Mafia prosecutor Antonio Ingroia, who charged in a letter to prosecutors that Berlusconi's campaign promise to refund the hated housing tax amounts to money for votes. Mascia said Berlusconi's promise to roll back IMU and refund the four billion euros collected was "bribery". "To obtain a refund for (the housing tax) IMU 2012, you have to vote for the PdL". He also complained that Berlusconi's campaign mail-outs to Italian homes amounted to a "scam" because the envelopes, bearing a signed letter from Berlusconi, "appear to claim to contain an IMU refund".