The Taoiseach is expected to comment later today on former taoiseach Albert Reynolds's criticism of him for accepting unusual payments in the early 1990s.
Mr Ahern is in Saudi Arabia today as part of a tour of the Middle East. He is expected to speak to reporters after making a keynote speech in Riyadh on the Middle East peace process.
The Mahon tribunal is to question Mr Ahern about the equivalent of nearly €114,000 lodged in bank accounts in 1993 and 1994 while Mr Ahern was minister of finance in the Reynolds government.
The Irish Times last September revealed that three sets of deposits were under inquiry leading to a political outcry.
The monies were a IR£39,000 (€50,000) loan from friends that was not paid back until after the controversy erupted; a £8,000 sterling (€12,000) payment for after-dinner speaking in Manchester; and approximately IR£40,000 (€51,300) Mr Ahern said he saved over many years.
The Taoiseach later conceded that he made an error of judgement in accepting the loan and the Manchester payments but insisted he had not broken any laws or regulations.
Mr Reynolds yesterday said in a radio interview he would not have allowed Mr Ahern receive the money, adding that it was likely such payments were forbidden under regulations at the time.
He was "shocked" by the revelation and was unaware of the payments until last September, he added.
The former taoiseach, who headed the Fianna Fáil/Labour coalition between 1992 and 1994, refused to be drawn on whether Mr Ahern should have resigned when the payments came to light.
Mr Ahern succeeded Mr Reynolds when the coalition broke up in 1994 in controversy surrounding the-then attorney general Harry Whelehan.