Former guards from the Nauru detention centre have spoken out against Wilson Security, accusing the Australian company of providing misleading evidence to Parliament.

The ABC's 7.30 program has obtained footage shot on cameras worn by Wilson Security staff showing guards at the centre preparing to confront detainees during the 2013 riot.

Since the parliamentary inquiry began, more guards have come forward claiming a spying operation on Greens senator Sarah Hanson-Young, first revealed in June, was more extensive than Wilson Security admitted.

The guards said the surveillance involved up to eight members of the Emergency Response Team and continued for the senator's full three-day stay on Nauru in December 2013.

Their accounts differ from concessions made by Wilson to the parliamentary inquiry that the rogue operation was "confined to an unauthorised observation from the car park" for 12 hours.

The former guards said orders were to follow and photograph the senator and make special notes about whom she met and when.

They also maintain the senator's room number at the Menen Hotel and her car registration were given to those executing the secret spy orders under the codename 'Raven'.

Apart from the guards, a doctor who worked on Nauru has also spoken out, telling the ABC the new border force laws are designed to silence the truth.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 9 minutes 3 seconds 9 m Spying and abuse described by Nauru detention centre's former staff ( Hayden Cooper )

Sydney paediatrician David Isaacs said the practical effect of the new laws was that "if you do report child abuse [on Nauru] you could get into trouble, that's evil," he said.

In a late submission made to the inquiry and seen by the ABC, a former Wilson guard also confirmed the Hanson-Young spying operation.

He said he spoke to a member of the Emergency Response Team who said "Ranger 1 had us film the whole thing, we've been watching her the whole time".

He added, "they gave everything to intel so we know what she's been doing".

The former guard also said Wilson management "made very clear that anyone who spoke to the senator would be dealt with".

Culture of shredding reports from surveillance operations

When allegations of the unauthorised surveillance surfaced in June, Prime Minister Tony Abbott disputed the characterisation of the allegations, saying Senator Hanson-Young was being "looked after" while on the island.

Former Nauru guards say Sarah Hanson-Young was spied on for the duration of her stay in Nauru. ( AAP: Mick Tsikas )

Immigration Minister Peter Dutton also dismissed the claims, saying the senator "makes these allegations which are completely unfounded" and "she gets most of her facts wrong most of the time".

"I think Senator Hanson-Young conducts herself in a way which is frankly an embarrassment to our country," he said.

At the final Senate hearing on July 20, Wilson Security said the surveillance operation on Senator Hanson-Young was confined to the night of December 15, 2013 when a Wilson supervisor took it upon himself to authorise two employees to watch the Menen Hotel.

According to the former guards, Wilson management panicked once details of the secret surveillance operation became known outside the small operation.

One guard said he witnessed the subsequent shredding of all documents collected throughout the surveillance operation, including photos of the senator and all notes.

Several of the former guards who spoke to the ABC described a culture of shredding reports.

"When writing reports they [Wilson management] always say make the use of force look as minimal as possible, even sometimes we are aware of reports that may look bad [for Wilson] and they'll [Wilson supervisor] take it and shred it and they'll ask you to rewrite it."

The former guard said this results in underreporting of abuse.

"When I started I was probably doing 10 [reports] per rotation, by the end I was probably doing one," he said.

Guards unaware of whistleblower hotline and never breath-tested

The guards also named the supervisor who ordered the operation and said that he was not disciplined after the operation became known.

Wilson Security told the inquiry the supervisor was stood down "with pay" but promoted nine months later.

The aftermath of a 2013 riot at the Nauru detention centre over the slow processing of claims. ( Supplied: Department of Immigration and Citizenship )

Wilson Security and Transfield, the company which is in charge of all operations on the island, have appeared three times before the Select Committee on Recent Allegations Relating to Conditions and Circumstances at the Regional Processing Centre in Nauru.

Throughout the hearings both Transfield and Wilson Security defended their operational policies, frequently pointing to a whistleblower hotline that until a few weeks ago no employee had used.

The companies also said they conducted regular alcohol tests on staff.

Former guards who spoke to the ABC said they were not made aware of a whistleblower hotline nor had they been breath-tested, nor seen any other employees breath-tested while on the island.

Several guards told the ABC alcohol was a problem and they had witnessed many guards turn up to work intoxicated.

In a July 21 Wilson Security meeting note seen by the ABC, the company acknowledged it has a long history of alcohol related incidents in both Manus and Nauru.

The parliamentary inquiry into operations at Nauru has uncovered:

67 allegations of child abuse - 30 of those made against staff

67 allegations of child abuse - 30 of those made against staff 33 allegations of sexual assault/rape

33 allegations of sexual assault/rape 11 Wilson staff disciplined or terminated in response to sexual abuse or the use of excessive force.

Paediatrician examined six-year-old who tried to hang herself

One guard recalled how he had to talk a transferee down for four hours when the asylum seeker managed to get hold of a large rock and a piece of wire and was attempting to drive it though his chest.

He said he had never received any training as a negotiator and "just winged it".

That guard said he is traumatised by what he experienced on Nauru and felt compelled to speak out.

Whistleblowers who worked on the island could face two years in jail if they speak out after the Border Force legislation came into effect on July 1.

Dr David Isaacs, a Sydney-based paediatrician who has run refugee clinics for 10 years, refuses to be silenced.

He said he has never seen more distressed families than the ones he saw on Nauru last December.

During his five-day visit, Dr Isaacs examined a six-year-old girl with rope burns around her neck after she attempted to hang herself using a fence tie.

Dr Isaacs said every child he saw on Nauru was suffering post-traumatic stress disorder.

"If I see child abuse in Australia and I don't report it I can get into enormous trouble," he said.

"If I see child abuse on Nauru and I do report it, I might go to prison for two years."

The inquiry is due to report in the coming weeks and the ABC understands it will make a number of key recommendations, including a demand that all children are removed from detention on Nauru, mandatory reporting of sexual abuse and a comprehensive drug and alcohol testing program on Nauru.

It may also recommend that the Immigration Department and Australian Federal Police conduct a full audit of all abuse allegations.