Nathan Tinkler says he rues the day he invested in NSW developer Buildev.
The former coal mogul has fronted the Independent Commission Against Corruption (ICAC) for a second time to face allegations he and top executives at the Hunter Valley company secretly funnelled money to NSW Liberal MPs.
Mr Tinkler is also accused of footing the bill for a smear campaign to unseat the former Labor MP for Newcastle, Jodi McKay, because she stood in the way of a Buildev coal-loader proposal worth tens of millions of dollars.
The watchdog has heard Tinkler's company Boardwalk Resources gave $53,000 to a Liberal front company, the Free Enterprise Foundation, and that $35,000 of this money wound up in the campaign coffers of the man who dethroned Ms McKay, sidelined Liberal MP Tim Owen.
But Mr Tinkler denied any knowledge of this, or a damaging anti-McKay leaflet campaign he is said to have funded, telling the ICAC he was nothing more than an investor in Buildev.
"An investment I deeply regret now," Mr Tinkler said.
He flatly rejected suggestions he knew of an alleged slush fund known as EightByFive, which is said to have been set up by a staffer to ex-NSW energy minister Chris Hartcher to fund political campaigns in the lead-up to the 2011 state election.
The ICAC has heard allegations Mr Tinkler gave orders to channel money to EightByFive through his horse-racing business, Patinack Farms, and that the payments were obscured by a sham consultancy agreement.
"I've never given permission for Patinack to be used for anything like that," Mr Tinkler said on Friday.
Property developers have been banned from making political donations in NSW since 2009.
The ICAC's long-running cash-for-favours probe has focused heavily on Buildev and other businesses with links to Mr Tinkler.
The saga has already dethroned Mr Hartcher and former police minister Mike Gallacher, forced two MPs to resign from parliament altogether and sent others to the crossbenches.