Australia is on the verge of signing a memorandum of understanding with the Southeast Asian nation, which would allow refugees processed on Nauru to resettle there.

A number of family groups at the Nauru detention centre have reportedly been told they will be sent to Cambodia if they're found to be genuine refugees.

But a spokeswoman for Immigration Minister Scott Morrison denied those claims on Wednesday, saying no such message had been given by the Australian government to transferees at Nauru.

"It is likely that transferees may have been made aware of media reporting on these issues," the spokeswoman told AAP.

Refugee groups and the Australian Greens have raised concerns about the resettlement plan, citing Cambodia's human rights record.

Federal Labor is also worried but won't say whether it will seek to block it.

Deputy Opposition Leader Tanya Plibersek says her party is "gravely" concerned about poverty and security in Cambodia, as it seeks more details on the proposal.

Prime Minister Tony Abbott has been accused of applying a double standard to the Cambodia deal, given his party's criticism and blocking of the Malaysia people-swap plan when Labor was in power.

A Nauru government spokesman said asylum seekers had been told that if granted refugee status, they would be temporarily resettled on Nauru for up to five years.

After that, they would be settled in a third country.

"No one has been told that they will immediately be sent to a third country," the spokesman told AAP.