136 children still in mainland detention

Immigration department boss Michael Pezzullo insists Wickham Point detention centre in Darwin is a child friendly facility and has a playground.

There are 136 children in immigration detention in Australia with 88 of them due to be transferred to Nauru.

Of the total number, 70 are being detained at the Wickham Point facility in Darwin which the Greens claim is not an appropriate place for children.

Immigration department secretary Michael Pezzullo, appearing before a Senate estimates hearing in Canberra on Tuesday, disagreed - pointing out that a playground had been built at the centre.