Vic opposition leader Guy referred to IBAC

Electoral commissioner Warwick Gatel said his organisation had exhausted its attempts to fully investigate what may constitute a breach of Victoria's funding and disclosure laws under the Electoral Act.

"We became aware of suggestions that Mr Catlin was alleged to have tried to circumvent donation disclosure laws," he said in a statement.

"It's my responsibility to ensure compliance with all electoral laws and ensure all participants are held to the same standard."

Mr Catlin allegedly asked a billionaire Liberal donor to make more than $100,000 in payments to his private marketing company.

A contract for the proposed arrangement was sent to Mr Guy's personal email address, but he has categorically denied it was signed or agreed.