But MSF later confirmed the memorandum of understanding with the Nauruan government was clear that refugees and asylum seekers would be provided services.
MSF had provided free mental health treatment to both refugees and the Nauruan population.
While the Australian government has retorted that staff from International Health and Medical Services (IHMS) visit Nauru, McPhun said that the refugees do not trust them given they are being paid by a government that prevents them from leaving or indefinitely imprisons them.
Dr Beth O'Connor, a psychiatrist, said that all the asylum seekers MSF saw were already suffering trauma from having to flee their country of origin, and many are suffering as a result of five years of indefinite detention.
Nearly all 900 asylum seekers and refugees on Nauru, including 115 children, have been on the island for more than five years, with no clear process or prospect of permanent resettlement.
MSF has been working independently on Nauru since November 2017.
MSF, one of the few groups to independently assess refugees at the restricted facilities, provided mental health care to asylum seekers and Nauru residents until the Pacific nation cancelled its contract on October 5.
One refugee said she had been receiving treatment for depression from MSF.
"Separating families and forcibly holding men, women and children on a remote island indefinitely with no hope or protection except in the case of a medical emergency is cruel, inhumane and degrading", said McPhun.
While numerous refugees on Nauru experienced trauma in their countries of origin or during their journeys, the Australian government's policy of indefinite offshore detention has degraded their resilience and reduced their hope that they will one day lead safe, meaningful lives. "Australia's policy of indefinite detention should be immediately stopped".
On Wednesday, Australia's Home Affairs Minister Peter Dutton reiterated that asylum seekers and refugees would not be relocated.
O'Connor also detailed the "withdrawal syndrome", which has been documented in many young people on Nauru. They were no longer eating or drinking sufficient amounts to keep themselves alive.
MSF's refugee patients reported being turned away from the hospital and police had taken those who had made suicide attempts to jail, she said.
"Seeing that level of deterioration in the children was really quite horrific".
Dr Christine Rufener, a clinical psychologist who also spent several months on Nauru, fought back tears as she spoke of her experiences on the island. "People feeling that their sense of self and any hope that they have about living a meaningful future has been irrevocably destroyed".
"MSF calls for the immediate evacuation of all asylum seekers and refugees so that they can complete their resettlement process in a place of safety with dignified conditions", he said.
Seventy eight refugees have attempted suicide since MSF arrived.