The mystery over a $20,000 payment to lobbyist Joe Tannous by Auburn council has deepened after it emerged the sum does not appear to have been recorded in official accounts.

Last week Fairfax Media revealed Auburn's former acting general manager Peter Fitzgerald authorised the payment to Mr Tannous' firm 1st State in June.

Under scrutiny: Joe Tannous. Credit:Simon Alekna

The engagement followed a demand by Transport for NSW for costly changes to a $12 million upgrade of Amy Street railway bridge at Regents Park that threatened to delay the project by two years. The department subsequently dropped its demands, leading Mr Fitzgerald to tell Auburn councillor George Campbell in September that ''the engagement of 1st State has been successful and it appears that the bridge project is proceeding''.

But no one, including new mayor Hicham Zraika, who has confirmed the $20,000 payment was made to 1st State, can say what Mr Tannous or the firm did for the money.