"Whilst .. I am not satisfied that the chief minister was not motivated by a desire to promote the public interest in the manner claimed, I think that a fair-minded lay observer might reasonably apprehend that there was a real and not remote possibility that the decision was influenced by partiality towards the Dexar Group," Dr Crispin wrote in his report tabled in the ACT parliament on Tuesday.

But a conclusion that perceptions of a conflict of interest were reasonable, did not, of itself, demonstrate a breach of the code of conduct, Dr Crispin found.

The Dexar Group is an arm of the Independent Property Group, a beneficiary of government business and a long-term Labor Party donor. Dexar holds a half-share in Purdon Planning, which also has a long list of government contracts under its belt.

In May, the ABC reported Mr Barr had made a video endorsement of Dexar, used by the group to attract overseas investors. As a result, Liberal leader Jeremy Hanson called on Dr Crispin, a retired judge and the ACT parliament's independent standards commissioner, to investigate.

Dr Crispin's report said speculation about Mr Barr's motives was understandable. "Political leaders rarely endorse particular companies or products and some people may have felt that the chief minister's decision to do so had aligned the status of his high public office with private business interests."

While political leaders did lead trade missions, this was not a publicly announced venture others could attend.

"Some people may have felt that the videotaped endorsement seemed more like a commercial television advertisement than a statement of government support for an initiative to foster international trade," Dr Crispin said.

"It was perhaps inevitable that some would wonder why the Dexar Group had apparently been singled out for such favourable treatment and speculate about the possibility of an ulterior motive, perhaps related to the groups' support of the ALP."

But Mr Barr had said he was helping ACT businesses expand overseas and attracting investment to Canberra. There was no suggestion the endorsement of Dexar brought any personal benefit to Mr Barr, there was no unequivocal indication of improper motive, the donations were a small fraction of overall donations to Labor, and there was no compelling reason to reject Mr Barr's assurance that he was motivated by the public interest, Dr Crispin said.

"Whilst some members of the community may remain skeptical of [Mr Barr's] explanation, in my view the suggested mala fides has not been established."

The code of conduct requires parliamentarians to avoid conflicts of interest or situations that could give rise to perceptions of conflict, and to act in the public interest.

Mr Barr had claimed his support for Dexar was in the public interest, but Dr Crispin said even if an action brought benefits to the territory, an observer might nevertheless question whether the public interest was the only motivation, "or merely a rationalisation of what The Canberra Times evocatively described as cronyism".

The endorsement was unusual, singling out the Dexar Group for favourable treatment. "It is also true that he spoke of the Dexar Group in very favourable terms, but that was perhaps to be expected in an endorsement that was essentially a sales pitch to potential international customers." The group had approached Mr Barr and there was no obvious reason why he should have invited other companies to seek a similar endorsement, Dr Crispin said.

The code should not be interpreted to mean parliamentarians could never deal with donors. And it said it was reasonable for ministers to prefer to deal with particular people or companies because of their performance - and partiality here should not be confused with favouritism.

Dr Crispin said he had not been asked to provide his opinion about whether Mr Barr should have endorsed Dexar or whether it was warranted; simply whether he had breached the code of conduct. The issues were potentially serious and an independent investigation had been clearly warranted. But no breach of the chief minister's duty had been substantiated.

A spokesman for Mr Barr said the report "speaks for itself that he didn't do anything wrong". He acknowledged the issues raised, but would not stop helping local businesses, and would consider further videos on "a case by case basis".