The claims are made in a report published by The Guardian Australia by 15 doctors who say they've worked at the Christmas Island facility.
Among the claims are that antenatal care does not meet Australian standards, that children are at high risk of depression, and that treatment drugs requested by doctors are not provided.
The Greens' immigration spokeswoman Sarah Hanson-Young says the doctors are worried they're participating in unethical conduct.
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"Now we find out that the medical assessments to determine whether they're fit to be sent to Nauru are being done within five minute," senator Hanson-Young says.
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"The other concerning aspect is that the blood test results are not even being received back before people are being dumped in Nauru or Manus Island. This is a very serious breach of the duty of care that the government has for these people."
The International Health and Medical Services group, which provides the medical care to asylum seekers on Christmas Island, has confirmed it's received the doctors' report.
