The Immigration Department believed medical staff contracted to take care of asylum seekers were advocating too strongly for detainees and it preferred doctors who complied with the Government's wishes, a leaked report reveals.

The frank confidential assessment by officials within the Immigration Department is contained in a draft consultant report obtained by the ABC amid claims the department has often overridden medical advice.

The findings are based on a meeting of eight senior bureaucrats from the department's offshore and health divisions who were asked in July this year to provide their views about the performance of contractor International Health and Medical Services (IHMS).

IHMS commissioned consultancy firm AMR to produce the report while it renegotiated a $900 million contract to provide medical services on Nauru and Manus Island.

This week, the department announced it had renewed the five-year contract with IHMS at an undisclosed sum.

Company 'risk averse' and 'advocating for transferees'

According to the leaked report, the department told IHMS the contract would be at risk if its complaints were not urgently addressed.

"The department were clear that the current status quo is unlikely to be accepted ongoing and if some or all of the key issues are not addressed then the department will need to look at other options," the report said.

Among the long list of complaints, the department said: "IHMS are seen to be risk averse and advocating for transferees beyond the services IHMS is contracted to deliver".

"The procedures being recommended were excessive and outside of the contract requirements," the report said.

The report also revealed the department was frustrated by IHMS medical advice to transfer detainees to the mainland.

IHMS often recommended transferring detainees to Australia, which "places the department in a difficult position as it is very difficult to reverse a medical recommendation once made".

"Discussion ensued on whether this is the result of IHMS advocating or being overly conservative."

To address the problem, the department said: "IHMS should recruit people who are able to follow the Government requirements in the contract".

"IHMS need to ensure medical staff who do reviews are not against Offshore Processing Centres (OPCs)," the report said.

The department pointed to an example of a psychologist who "regularly deemed transferees were not fit to return to an OPC".

Earlier this year, the Australian Human Rights Commission inquiry into children in detention heard evidence from doctors that the department would often ignore medical advice and had tried to cover up the extent of mental health problems in immigration detention.

'Incorrect, incomplete information' frustrated department

The leaked report also outlined the department's frustration with information provided by IHMS that was "incorrect, incomplete or not understood".

The department also said IHMS relied "too heavily on medical terms".

"This has significant implications for the department given the political sensitivities around OPCs," it said.

The department said at least one clinical report had "large pieces of information missing".

"One of the reports related to a transferee who died in custody which put the department in a difficult situation as there was not sufficient information available to understand the situation."

The report does not name the detainee but it may relate to Iranian asylum seeker Reza Barati who died during the riot on Manus Island.

A spokeswoman for IHMS would not be drawn on whether IHMS had modified its practices in response to the department's complaints and said the draft did not represent any final report.

Despite the draft report's findings, Immigration Minister Scott Morrison maintained his department was satisfied with the performance of IHMS.

"It is clear the department has been able to resolve any issues regarding the service provider over the course of the tender process," Mr Morrison said.

"IHMS has been selected as the preferred tenderer and the Minister is confident the department would not have reached that view if they were not confident of the service that is being provided.

"The Minister's expectation is that IHMS would do their job and the department would do its job. Their obligations and responsibilities are clear and the Minister expects them to be adhered to," he said.