An escort who says she met with Craig Thomson on at least six occasions says the former MP lied when he denied using union-issued credit cards to pay for sex.
Thomson, 49, is accused of using the cards to pay for escorts and personal expenses while he was the national secretary of the Health Services Union and a Labor MP.
He has pleaded not guilty to dishonesty offences and has previously denied in media interviews using the cards to pay for prostitutes.
But a former Sydney escort who worked under the name Misty said Thomson was a regular client of hers who had paid for her services on at least six occasions.
"I have since seen him on TV and in the media deny that he used the services of prostitutes," she said in a statement tendered to the Melbourne Magistrates Court on Tuesday.
"He is lying and I am in no doubt that the Craig I performed a number of sexual services for over a period of time is Craig Thomson the politician."
The woman said Thomson would often provide her with champagne, and sometimes paid for more time with her so they could chat.
Copies of vouchers allegedly made from Thomson's union-issued card to the escort agency parent company Keywed Pty Ltd were also tendered as evidence.
In a separate statement, Keywed's manager Kati Traunwieser said she recalled a union credit card being used for a transaction in April 2005.
"I don't have any proof that it is him except for his signature on the voucher. I did not see him at the times of the transactions," she said.
Prosecutor Lesley Taylor SC said Thomson knew he was not authorised to use the cards for personal expenses.
"His application of union policies on others and his conduct in explicitly and implicitly masking transactions demonstrates that knowledge," she told the court.
"These expenditures were unauthorised according to the legislation and the (union's) rules."
Ms Taylor said Thomson had voluntarily given an interview to Fair Work Australia, in which he conceded that escorts were not a legitimate union expense.
Thomson faces 145 dishonesty charges over the alleged misuse of $28,449 between 2002 and 2008.
His barrister, Greg James QC, is expected to make submissions to the hearing on Wednesday.