Anton Piek, now an acting supervisor at Waikeria Prison in Waikato, spoke exclusively to Fairfax Media to strongly deny assaulting seven asylum seekers, including Iranian Reza Barati, who died later in the riot.

Mr Piek had not been identified until now. He is the first guard involved on the frontline of the riot to speak out, saying the public had not been told the truth of what happened. He released a photograph of injuries he sustained during the riot, and claimed asylum seekers had armed themselves with shanks, spears and axes.

"It was chaos. I'm a trained professional, I did what I had to do, but within the boundaries of the law. I didn't assault anyone, I didn't use excessive force," he said.

During protests in February, fences were pushed over and Papua New Guinea nationals gained access to the compound. Local people and police dragged asylum seekers outside to be beaten, an Australian government report found. One man lost an eye, another had his throat cut, and one was shot in the buttocks. At least 69 people were treated for injuries.

The report found Mr Barati was killed after being hit from behind with a heavy stick, then being kicked by a mob of about 10 people and finally having a rock dropped on his head.

It was reported last month that PNG police had arrested two suspects over the alleged murder of Mr Barati and were pursuing two expatriate former guards.

Australian Immigration Minister Scott Morrison told media in May that the only expatriate guard who was accused by multiple witnesses was a New Zealander.

A witness statement obtained by Fairfax Media says a New Zealand guard for G4S, which managed security at the time, called Anton, came into the witness' dormitory room and began hitting his brother, before turning on the witness and five other asylum seekers.

"[My brother] said to him 'I beg you, don't hit me because I am sick, I have diabetes'," the witness said. "But he hit him with force and said to him 'I hate asylum seekers'," said the statement, made to the PNG government and dated March 26.

Mr Piek said the statement was full of contradictions and "exaggerations" and though he knew Mr Barati, who he described as a "bully" and "standover man", he was nowhere near him on the night of the riot.

"All these asylum seekers are making statements that I assaulted them and you think 'gee, I must be superman being all over the place in all these different compounds."

PNG police would not comment on whether they were pursuing any expatriate guards, saying the case was ongoing and a G4S spokesman said PNG police had yet to make contact with the company about the alleged involvement of their staff.