SECURITY contractors at Nauru offshore detention centre admitted there were "allegations of misconduct" that had arisen at the centre.
The comments came during a sometimes heated Senate inquiry in Canberra on Tuesday into the conditions asylum seekers face at the centre.
That inquiry follows an investigation into allegations of sexual assault and of sexual favours being traded for cigarettes at the centre.
In a submission to the inquiry, Dr David Isaacs, who worked at the centre briefly, also claimed a woman had reported being raped by a cleaner.
Security and welfare at the centre is run by Transfield Services under a $1.2 billion, 20-month government contract.
Transfield Services contracts out security guard and cleaning services to Wilson Security.
Wilson's security contract manager Brett McDonald told the inquiry he was aware of at least one incident where a detainee was "mishandled", and some cases where employees had been moved on or terminated. Transfield Services' chief executive of operations Kate Munnings told senators that despite the firm's commitment and best efforts, "some allegations of misconduct have arisen".
The committee also heard asylum seekers were living in mouldy tents in 30-degree heat without air-conditioning.
Transfield witnesses said some young families were in air-conditioned units, but most were living in tents.
Administrative buildings were air-conditioned.
Transfield Services witnesses told the committee they were still working with the Australian Government to improve the conditions, but progress had already been made since it took over in February last year.
However, many questions from senators from all political parties went unanswered, with witnesses taking detailed questions on notice.
The inquiry follows a government review of misconduct allegations at the centre, and contractors have already acted on many recommendations from that review.
The Senate inquiry is due to report its findings to parliament in mid-June.
Update your news preferences and get the latest news delivered to your inbox.