All asylum seeker children have either been removed from Nauru or are about to leave the island, Prime Minister Scott Morrison has confirmed.

Key points: Mr Morrison said the four remaining children would travel to the US with their families

Mr Morrison said the four remaining children would travel to the US with their families But he didn't put a date on when the children would leave Nauru

But he didn't put a date on when the children would leave Nauru Key crossbenchers have been pressuring the Government to get the children off the island

Mr Morrison made the announcement with Immigration Minister David Coleman on Sunday morning.

"There were 109 asylum seeker children on Nauru at the end of August 2018 at the time we took on our respective roles as Prime Minister and Minister for Immigration," Mr Morrison said.

"There are now only four asylum seeker children on Nauru and they have all been approved for departure to the United States of America with their families."

It is not known exactly when the four children and their families will leave the island.

Mr Morrison praised Operation Sovereign Borders in his statement, criticising Labor's asylum seeker policy proposal, saying it would "unravel" the border protection framework put in place.

"Australia has one of the most generous humanitarian immigration programs in the world, but we can only do it by maintaining strong borders and insisting people come the right way," he said.

"We have secured our borders, we stopped the boats and the tragic drownings at sea.

"And we have been supporting children compassionately without putting our strong border security at risk.

"We have got the balance right."

The issue of children on Nauru has been a contentious one, with key crossbenchers in the House of Representatives saying they would use their balance-of-power position to push for the children to be removed.

Opposition Leader Bill Shorten welcomed the news the children would be leaving.

"I do believe if the crossbench, and the Opposition, and some of the progressive Liberals hadn't pursued this, I do wonder if the children would have been off," he told ABC TV's Insiders program.

Greens leader Richard Di Natale also argued the crossbench had forced the Government's hand on the issue.

"These kids now will have years of counselling ahead of them, these are kids who, many of whom will be damaged for life," he told Sky News.