Damning email and text messages shown at the Independent Commission Against Corruption on Tuesday reveal Mr Tripodi predicted a rural block of land at Edmondson Park would "rise in value substantially" if plans for a South-West Rail Link train station went ahead.

"It is a strategic piece of land which [government development company] Landcom will probably come knocking to buy," Mr Tripodi wrote in a February 2011 email to Tinkler business partner Darren Williams.

Mr Tripodi, then a government backbencher, also offered to take Mr Williams on a tour of the area, saying in a February 17 text message: "How about a bite at Liverpool and then off to the 2 sites."

ICAC is investigating allegations that Mr Tripodi "quite improperly took steps directly to benefit" Mr Tinkler's property development company, Buildev. This included steps taken to help Mr Tinkler secure approval for a coal loader in the Newcastle suburb of Mayfield, a project that was contrary to Labor government policy.

Counsel assisting the ICAC, Geoffrey Watson, SC, asked Buildev co-founder David Sharpe if it was "public knowledge" that Landcom was in the midst of buying properties along the rail line.

"I wouldn't know," Mr Sharpe replied.

Asked what would motivate Mr Tripodi to give Buildev a tip-off, Mr Sharpe agreed with the sarcastic suggestion that Mr Tripodi was simply acting "out of the goodness of his heart".

"St Joseph of Tripodi," Mr Watson retorted. "I mean, come on, Mr Sharpe, this is just ridiculous. Obviously the man is making a commercial link with you."

Later on Tuesday, the inquiry heard that former Labor treasurer Eric Roozendaal invited Buildev's Mr Williams to be his guest in the government suite at the V8 Supercars at Homebush in December 2010 while the company lobbied him over its coal loader plans.

Mr Roozendaal is also being investigated over allegations he improperly took steps to benefit the company while in office.

Documents shown at ICAC reveal Buildev had a so-called "Eric strategy" for getting the then treasurer to block a rival project to the coal loader.

"We need to meet with Eric next week to head this off," Mr Sharpe wrote in an October 2010 email about the rival project.

Mr Sharpe said he did not believe the meeting went ahead but agreed Mr Roozendaal stopped the rival plan going to a government board for consideration.

Mr Sharpe said Buildev regarded Mr Roozendaal as a "nice guy" and representatives of the company met with him about five times, including once at the upmarket Japanese restaurant Sake in The Rocks.

"What time will Eric get there as Nathan wants to get [to] see Eric," Mr Sharpe wrote in a January 2011 email to Mr Williams.

In February 2011, Mr Tinkler wrote to Mr Sharpe: "I just want this thing f---  approved so we can move on."

Documents show Buildev executives also met with Labor staffer Ian McNamara, who has temporarily stood aside as Opposition Leader John Robertson's chief of staff during the inquiry.

In an email headed "Summary Ian McNamara", Mr Sharpe wrote that "we need to work together as a team".

Mr McNamara is expected to give evidence later this week.