A whistle blower is suggesting New Zealand guards have been involved in water-boarding and other torture of asylum seekers in Nauru.

The man, who works for Wilson Security, made the explosive allegations in a submission to an Australian parliamentary inquiry examining abuse at the centre.

He outlined a practice called "zipping" where guards secure asylum seekers to metal frame beds that are thrown into the air so they crash onto the floor.

The guard claimed Wilson Security staff are heavily comprised of former Australian and New Zealand soldiers who harbour ill will towards people from countries where they served in war.

Wilson Security has rejected the water-boarding and zipping claims and dismissed the submission as "inflammatory, incorrect and misleading".

The submission also alleges guards regularly goaded asylum seekers into reacting and then bashed them, but the company denied there was a "random cycle of abuse".  The guard accused his employer of regularly shredding incriminating documents, a claim the security firm also denied.

The whistle blower described one instance where Wilson Security staff bashed a male refugee senseless following an incident at the Jules nightclub in Nauru and the refugee was later thrown from the club's balcony.  The refugee had allegedly touched a female aid worker inappropriately, he explained.

The company's version of events is that the intoxicated refugee was removed from the venue after sexually assaulting the female worker, who did not wish to press charges.  The refugee returned later with two companions and confronted staff who had removed him.  "They defended themselves and there was a resulting altercation," the company said, adding there were no serious injuries and the police were not called.

The company insisted its training is up to scratch and staff are required to treat asylum seekers with respect and dignity based on a code of conduct.