The United Nations Children's Fund says Australia is violating the rights of children being sent from Nauru to Cambodia under the refugee transfer agreement.

UNICEF has joined a chorus of international agencies in raising concerns over the $A40 million refugee resettlement pact with Cambodia, with the first of the refugees expected to be flown out from Nauru this week.

UNICEF has warned that no government policy or action should knowingly put children's lives or their well being at increased risk.

A UNICEF spokesman, Chris de Bono, said Australia and Cambodia needed to be aware of their international obligation under the convention to protect children.

"The world has an expectation that as signatories to the convention on the rights of the child, whatever action they take, they will have given due consideration to its impact on children and they will put the best interests of the child as a primary concern in making any decision," de Bono told AAP.

Analysts say Australia may be in breach of the convention given the threat of the children's rights being violated due to the transfer from Nauru to Cambodia.

A recent Australian report by a former integrity commissioner, Philip Moss, on conditions at the Australian funded centre in Nauru was highly critical and detailed allegations of rape and assault, self harm among children, and trading of sexual favours for drugs.

The UNICEF comments come against a backdrop of heightened fears over the welfare of the detainees both in Nauru and at detention centres in Australia, especially the Wickham Point facility in Darwin.

On Saturday a number of detainees with at least one three-month-old child were flown from Darwin to Nauru despite protests.

In the coming week, possibly as early as Monday, a charter plane is expected to fly out from Nauru with some 10 refugees for resettlement in Cambodia.