Premier Dominic Perrottet announced the crackdown after getting an independent review into the recruitment of former deputy premier John Barilaro to a lucrative US trade envoy job.

"Mistakes have been made, not just at one point, but at various points along the recruitment process," he told reporters on Tuesday.

"The process was just flawed from the outset."

The review into the bungled appointment was conducted by former NSW Public Service commissioner Graeme Head.

"The entire process that has been undertaken has been incredibly disappointing," the premier said.

He flagged an overhaul of the ministerial code of conduct "to prevent for a period of 18 months a minister from accepting any offer of employment within a public sector agency that reported to them in the previous two years".

The code will also be amended to prevent ministers from seeking to influence department secretaries "in relation to their employer functions".

Mr Perrottet said fundamental errors were made but stopped short of blaming public servants for the saga that saw Mr Barilaro appointed in June as the New York-based commissioner with an annual salary of $500,000.

"The clear processes that should be in place were not there and were not followed," Mr Perrottet said.

Former trade minister Stuart Ayres resigned earlier this month after a draft excerpt from the Head review "raised questions" about whether he had breached the ministerial code of conduct.

Mr Head concluded "this process did not occur at arm's length from the then minister" when considering Mr Ayres's interactions with Investment NSW Secretary Amy Brown, who was instrumental in Mr Barilaro's hiring.

Mr Barilaro relinquished the position two weeks after his appointment was announced, amid allegations of "jobs for the boys", conceding his position was untenable and a distraction.

Mr Head interviewed Mr Barilaro as part of the review, which found he had not committed any wrongdoing during his time as a trade minister.

Mr Head's review made eight findings and 13 recommendations, and the government will adopt 12 of them.

Another change to the trade roles will be recruitment through the public sector rather than through a ministerial or a "statutory" appointment.

The premier said he "can't change" previous mistakes but vowed that he would institute "robust processes" prompted by the inquiry's recommendations.

"The government is committed to transparency, accountability, and acting in the best interests of the people of NSW," the premier said in a statement.

But Labor MP Daniel Mookhey, who is on the upper house committee that's also inquiring into the appointment, was scathing about Mr Perrottet's reluctance to name officials responsible for the debacle.

"It is disappointing that Premier Perrottet is trying to pass this off as a bureaucratic bungle when everyone else can see this is a red hot political scandal," he said.

His fellow inquiry member Penny Sharpe also criticised the ministerial "meddling" that contributed to highly accomplished candidates being dumped in favour of Mr Barilaro.

"There were two very well qualified women who were the preferred candidates ... and they didn't get a chance because of the meddling of his (Mr Perrottet's) ministers through this entire process," she said.

The inquiry's terms of reference have now expanded to look at all the trade commissioner roles, with a focus on the agent-general position in London.

Mr Barilaro was scheduled to appear at the inquiry on Friday but withdrew citing mental health reasons.

The inquiry will resume on Thursday.

Australian Associated Press