Former Fianna Fáil TD and junior minister Ivor Callely has been arrested in Dublin.
Mr Callely was arrested at his home in Clontarf this afternoon by detectives from the Garda Bureau of Fraud Investigation.
Gardaí began an investigation after allegations emerged that false invoices may have been submitted and monies paid to Mr Callely for mobile phone expenses.
The former Senator was taken to Irishtown Garda Station for questioning.
He is being held on suspicion of breaching the Theft and Fraud Offences Act in relation to the use of false instruments.
His house and office were also searched.
Earlier this year, the Standards in Public Office Commission sent a report to the DPP but ended its own investigation into mobile phone claims made by the former politician because he had ceased to be a member of the Seanad.
The Commission had been asked to investigate the complaints by the Seanad Select Committee on members' interests.
The independent body decided that Senator Callely might have committed an offence relating to the performance of his functions as a member of the Seanad, but was obliged to end any probe when he ceased to be a Senator.
The complaints followed a newspaper article alleging that Senator Callely had made claims for mobile phone expenses using invoices from a firm that had ceased trading some years earlier.
Mr Callely subsequently paid back over €3,000 to the Oireachtas arising from the claims.