Peter Bollas, the suspended manager of Metro Trains' fleet, told Wednesday's Independent Broad-based Anti-corruption Commission hearing he took monthly payments up to $10,000 from Transclean managing director George Haritos.

The payments were to "assist and grow" Transclean's business, with the company contracted to clean Metro and V/Line trains.

Suspended V/Line boss James Pinder is also alleged to have profited to the tune of at least $320,000 in electronic transactions, plus cash payments, to further Transclean's interests.

All three men are the subject of an IBAC investigation into serious alleged conflicts of interest and procurement impropriety.

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In tapped phone calls, Mr Bollas and Mr Pinder discuss how to approach Mr Haritos for suspected cash kickbacks.

"Tell him like this: 50 each. Done. We're not greedy f***ers," Mr Bollas says in the call from April 21 this year.

Mr Pinder responds: "He always calls it a sprinkle, don't he? 50s good."

In another call between the pair on April 30, Mr Pinder tells Mr Bollas: "You and I will milk this for as long as we can, yeah?"

"We have been hand-feeding him everything for the last four or five years. Everything he's got, he's been delivered it on a plate."

Mr Pinder, however, denied the accusations under questioning from counsel assisting Paul Lawrie and commissioner Robert Redlich, claiming the trio were involved in a gambling syndicate.

"A reasonable person looking at this from the outside and listening to those calls and reading those transcripts would say, 'this is Mr Bollas and Mr Pinder talking about how much Transclean's making," Mr Lawrie said.

"... How much extra they're making, despite the discounts during the COVID response, and 'how much we can milk from them over and above our regular monthly milking'.

"Do you see how that might be a reasonable conclusion that someone might reach looking at this?"

Mr Pinder replied: "I can see that."

Mr Bollas told the hearing on Wednesday he had never been in a gambling syndicate.

The commission has previously heard Mr Pinder and Mr Haritos used burner mobile phones, subscribed in the name of Transclean associates, for almost four years to communicate secretly with each other and Mr Bollas.

Mr Pinder has admitted to writing Mr Bollas handwritten notes - shown at the hearing - after his house was raided by IBAC officers.

"They will be listening to phones and probably still are," one read.

"This may not end well - prepare for the worst.

"We need to stick together."

The hearing continues on Thursday.

MONDAY: The boss of Victoria's regional train network has been accused of using a secret burner phone and having part of his Melbourne home paid off by a cleaning contractor.

The Independent Broad-based Anti-corruption Commission on Monday opened public hearings into allegations senior public officials improperly influenced the awarding of major contracts with V/Line and Metro Trains.

Counsel assisting Paul Lawrie said investigators had uncovered new and serious alleged conflicts of interest and public contract impropriety.

In his opening address, Mr Lawrie said several "suspect" bank account transactions were detected in late 2019 between V/Line boss James Pinder and Transclean.

The cleaning company was hired by V/Line in May 2018 on an initial three-year, $17.2 million contract that had scope to be extended by four years for an extra cost of about $23 million.

Transclean was also awarded contracts with Metro Trains and Melbourne's tram operator, KDR.

Mr Lawrie told the commission that Pinder, Metro Trains' head of fleet operational support Peter Bollas and Transclean managing director George Haritos had past ties.

All three will be called to give evidence during the Operation Esperance public hearings, with Mr Pinder facing questioning on Monday.

"For a period of nearly four years, James Pinder and George Haritos have used a pair of burner mobile phones, subscribed in the name of Transclean associates to communicate secretly with each other and with Peter Bollas," Mr Lawrie said.

"These secret phones came into use soon after James Pinder's appointment as the chief executive officer of V/Line in late 2016."

Burner phones are cheap pre-paid mobile phones that can be disposed of easily.

A $100,000 deposit on Mr Pinder's current residence at Williamstown, in Melbourne's southwest, was also made by a Transclean associate, the commission was told.

"This was the first of several structured payments between late 2018 and early 2019 totalling at least $320,000," Mr Lawrie said.

"These payments to James Pinder were in addition to suspected regular cash payments to both him and to Peter Bollas to advance Transclean's interests in the public transport sector."

Mr Pinder stood down as V/Line chief executive in August when it emerged he was under investigation by the corruption watchdog.

AAP