The network is being sued for defamation in a NSW Supreme Court lawsuit filed by Synergy 360 and its CEO David Milo over four Sydney Morning Herald articles.
They are seeking damages and argue the reports, published from November 2022 to March 2023, have ruined their reputation.
David Crowe is one of the journalists whose articles Synergy 360 is suing over. (Alex Ellinghausen/AAP PHOTOS)
But Nine has hit back, saying the articles were public interest reports on the truth and honest opinions of journalists Nick McKenzie and David Crowe.
In a filed defence made public on Tuesday, Nine says it can prove Synergy and Mr Milo "engaged in corrupt conduct" by Mr Robert when he sat on the Liberal frontbench.
Mr Robert was a "close friend" of Mr Milo and had links to a firm called Australian Property Trust which held shares in Synergy 360, the defence claims.
After a parliamentary inquiry, Mr Robert was referred to the National Anti-Corruption Commission in September over claims Synergy channelled money to a company linked to him to win government work.
Mr Robert has previously denied any impropriety, labelling the NACC referral as a "farce" and example of political payback.
In its defence, Nine says advice given by the then-Liberal MP was secretly passed to Mr Milo and Synergy to help six clients, including Unisys Australia, Oracle Corporation and Infosys Technologies.
Nine said McKenzie and Crowe took reasonable care to separate what was known from allegations. (Joel Carrett/AAP PHOTOS)
"(Mr Milo and Synergy) received a financial benefit from the conduct, including in the form of retainer payments and success fees from clients of (Synergy) who procured federal government contracts," Nine's defence says.
This conduct was not publicly disclosed at the time and Mr Robert used his personal Gmail account instead of his government address "for the purposes of keeping such communications secret", Nine says.
The MP's alleged corrupt conduct included trying to hook up Taiwan-based Formosa Plastics Group to Gold Coast City Council in mid-2017 to replace its city lighting.
In August that year, Mr Robert is claimed to have made a "gypsy's warning" to encourage IT provider Unisys Australia to sign a contract with Synergy.
The US-based Unisys eventually tried to sell its border security software Linesight to the Australian government in October 2017.
An email from Synergy director Khamphone "Kham" Xaysavanh to Mr Milo celebrated the "bloody amazing" amount of money to be garnered from the Unisys deal given the consulting firm had only been incorporated a few months earlier in April.
"Some companies don't even make a profit let alone clear $100,000 in the first 3-4 months of operation. The year isn't over yet so let's aim for $1M within the FY 17-18!!!" he wrote.
Further advice was allegedly sought for two of Synergy's clients, IT companies Oracle and Infosys, which put up pitches for defence force contracts with the government.
Synergy's boss is accused of lying during a phone call to Nick McKenzie. (Dan Himbrechts/AAP PHOTOS)
Mr Milo is accused of lying during a phone call with McKenzie by denying Mr Robert had provided his firm with advice.
He then hung up the call.
"It may be inferred that (Mr Milo) lied to avoid proper scrutiny by McKenzie and Crowe of his and (Synergy's) relationship with (Mr Robert)," the defence reads.
Synergy engaged in lobbying activities despite not being listed on the lobbyist register and had breached the code of conduct, the network said.
Nine backed up its journalists, saying McKenzie and Crowe took reasonable care to ensure the articles separated what was known from allegations.
McKenzie reviewed the reliability of a tranche of emails relating to Mr Milo sent to him by a confidential source in November 2022, Nine said.
The matter will next come before the court on April 26.
Mr Robert, who represented the Queensland seat of Fadden, resigned from parliament in May.
He did not respond to AAP's requests for comment.
