The former immigration minister Scott Morrison has refused to apologise for airing allegations about Save the Children staff “coaching” asylum seekers to self-harm in the Nauru processing centre, after an official review found a lack of evidence to substantiate the claims.

Philip Moss, a former integrity commissioner, said he had uncovered no conclusive information that contract service providers on Nauru had facilitated protest activity, encouraged self-harm or fabricated assault allegations.

In a report released by the government on Friday, Moss called on the immigration department to review its decision in October last year to eject 10 Save the Children staff members from the Nauru centre. Their dismissal is currently the subject of a legal challenge.

Morrison previously said he had received information indicating “that there may have been a level of coaching and facilitation and co-ordination amongst people who are working for one of our service providers”.

“Now 10 people in relation to those issues have been asked to leave Nauru and that instruction was given to Save the Children last week,” Morrison told 2GB on 7 October.

In a press conference on 3 October announcing the Moss review, Morrison said service providers were “employed to do a job not to be political activists”.

“Making false claims and worse – allegedly coaching self-harm and using children in protests – is also completely unacceptable, whatever their political views or whatever their agendas,” Morrison said at the time.

Morrison, who is now the federal social services minister, was asked on Sunday whether he conceded his comments about Save the Children staff had been wrong.

He replied that the allegations had been presented to him in a formal report, and he took action by referring that information to the Moss review.

“I’m pleased that the Moss review has investigated those allegations and the other very serious allegations and I’m pleased that they’ve come back and the government has accepted all of those recommendations,” Morrison said on the sidelines of the New South Wales Liberal party campaign launch.

“It was my action on seeing all of these allegations not to draw any conclusions on them at all, as I said at the time, and to refer them off to an independent review.”

When asked directly if he would apologise to Save the Children, Morrison said: “Well, I made no allegations; I referred allegations for a proper inquiry.”

The Greens senator Sarah Hanson-Young demanded an apology.

“The Abbott government’s eagerness to shoot the messenger meant that, in this case, they shot first and asked questions later,” she said on Sunday.

Moss said he had been unable to obtain information supporting the allegation of contract service provider staff members coaching or encouraging transferees to engage in self-harm, other than two intelligence reports compiled by Wilson Security in September 2014.

He said one of those reports, on 28 September, concluded it was probable there was a degree of internal and external coaching, and encouragement, to achieve evacuation to Australia through self-harm actions.

Moss said another intelligence report two days later concluded it was probable some staff were coaching and encouraging self-harm, and it suggested that incident reporting by Save the Children staff had been “increasingly emotive in recent weeks”.

The 30 September intelligence report cited a July report in the Australian newspaper headlined “Advocates coaching asylum seekers to self-harm for political reasons”.

The newspaper article was based on an interview with Greg Lake, a former immigration department official, who referred to “certain prominent advocates who will coach and encourage asylum-seekers to self-harm as a political protest”.

Moss said: “The article did not refer to any encouragement to self-harm by contract service providers in Nauru or more specifically by Save the Children staff members.”

A ministerial submission to Morrison on 2 October said, in part, that the 30 September intelligence report “raised concerns – not yet verified – about the veracity of allegations of mistreatment towards transferees in the past few days, which was reported widely in the Australian press”.

The same day the immigration department directed Save the Children to remove 10 employees from working on Nauru. “No details of any specific allegations concerning the 10 Save the Children staff members were provided to the department before it issued the notice to remove and the department has confirmed that it did not request such details,” the Moss review said.

On 3 October, Morrison called a media conference to announce the Moss review and the removal of the Save the Children staff.

His announcement came hours after the Daily Telegraph reported the coaching allegations under the headline “Truth overboard”.

Morrison said at the time that he was “drawing no conclusions about any of these matters” but added that “the public don’t want to be played for mugs with allegations being used as some sort of political tactic in all of this”.

Morrison referred to “the orchestration of protest activity and the facilitation of that protest activity on Nauru, including the tactical use of children in those protests to frustrate the ability of those who work at the centre to deal effectively and safely with those issues, their coaching and encouragement of self-harm for people to be evacuated off the island and fabrication of allegations as part of a campaign to seek to undermine operations and support for the offshore processing policy of the government”.

Departmental officers told the Moss review the removal of the staff acted as “a circuit breaker” and reduced protest activities.

Allegations of confidential information being leaked to the media and advocacy groups were referred to the Australian federal police and therefore were not investigated by Moss.

Moss said the review had “not obtained any information which substantiates the alleged misconduct in terms of inappropriate attitude, emotive reporting and links to refugee advocacy groups in relation to the 10 Save the Children members”.

In the report, Moss noted two specific allegations of rape of two women at the Nauru centre; concluded that Nauruan guards may be trading marijuana with detainees in exchange for sexual favours; found many people transferred to the centre were apprehensive about their personal safety; and suggested there was under-reporting of sexual and other physical assault.

The opposition’s immigration spokesman, Richard Marles, reaffirmed Labor’s support for offshore processing but said “that does not mean that asylum seekers are the enemy”.

“If we owe asylum seekers anything, and we do, it is that the facilities that we provide afford asylum seekers with safe, dignified and humane refuge,” he said.