Liberal Leader Jeremy Hanson has also used Question Time on Tuesday to question the involvement of former Labor deputy chief minister, now development consultant, David Lamont in the Brumbies land deal.

The issue goes to the bitter battle that has raged at top levels of the Brumbies, with Brumbies chief executive Michael Jones raising serious concerns about the Griffith development and move to the University of Canberra through a series of negotiations between 2009 and 2013.

The Brumbies first announced plans to sell the Griffith headquarters in 2009, and announced the eventual sale, for $11.375 million, in 2013. The site is being developed for apartments by Graham Potts's Amalgamated Property Group.

Mr Lamont, through a company half-owned by his wife, is project adviser for the University of Canberra on campus development, including student accommodation, health and sport projects.

Mr Hanson raised some of the issues in Question Time, saying Andrew Barr, then treasurer, had in January 2012 signed an instrument to consider a lease variation for the Griffith site. In 2013, the government had called in and approved the planning change for the site, and later announced the waiver of the lease variation charge for the development, worth $7.5 million.

"The purpose of waiving [the tax] was supposedly to provide a windfall for the Brumbies and local rugby for community purposes," Mr Hanson said. "Minister, who is in receipt of the $7.5 million of benefit?"

"The Brumbies and local rugby," Mr Barr responded.

The Liberals also asked what conversations Mr Barr had had with Mr Lamont about the deal. Mr Barr did not directly answer the question, responding that he had had conversations with the Brumbies' chief executive and board chairman and the university's vice-chancellor.

Asked what involvement Mr Lamont had in the transaction and the $7.5 million tax concession, Mr Barr responded, "In relation to the ACT government, none, in relation to the University of Canberra and or the Brumbies, that's a matter you'll need to raise with them."

Mr Lamont told The Canberra Times earlier this month that the move to the University of Canberra was arranged by the Brumbies, university officials and their respective lawyers.

"I was not involved in any of those details or anything to do with that formal relationship, " Mr Lamont said.

Asked again about the deal last week, he said the issues were "subject to orders of the court and I am unable to comment".

The questions came has Labor and Liberal clashed over ethical standards, when Liberal Andrew Wall brought on debate about the integrity of Labor ministers, including the controversy that has surrounded minister Meegan Fitzharris since news broke that her husband, Pierre Huetter, was working with Mr Lamont on the GWS Giants bid for Manuka Oval. Mr Huetter has now resigned the post.

Liberal Leader Jeremy Hanson said the message was that if you wanted to do business in Canberra, it was best to have Labor mates, in the unions or as lobbyists. The government had started to "rot", he said.

But Mr Barr hit back, saying Labor had taken on the task when it came into government in 2001 of restoring public trust after "the crushing spread of appalling abuses" by the former Liberal government.

The Liberals were insulting the memories of Canberrans, pretending that none of the "ministerial disgraces" of their time in government had ever happened. He pointed to the Carnell government's overnight loan at the end of the financial year to pay for a blow-out at the Bruce stadium, the decision to paint the stadium grass green, and an incident in which Kate Carnell left the scene of an accident in 1997.

"It's not something people forget," Mr Barr said.

The code of conduct did not require "inhuman perfection" but required ministers to correct the public record at the earliest opportunity, he said. Labor had appointed a commissioner for standards and an ethics and integrity adviser, extended the code of conduct to members' staff and introduced a lobbyists register, he said.