Charities and community groups say they are ready to help the Federal Government start moving families out of immigration detention centres and into community accommodation.

Immigration Minister Chris Bowen has announced more than 700 children and their families will be moved out of detention centres for the sake of their development and mental health in the next eight months.

Uniting Care's Lin Hatfield-Dodds says charity and church groups are ready to help.

"We've been working with people exiting detention for years now," she said.

"So right across the community sector, there's a lot of staffing expertise and often those people are working part-time.

"There's a latent capacity there that we can crank up almost immediately. The trick is going to be finding accommodation options. And what we've been hearing is the Government is very serious about sitting down with the non-government sector and saying how, together, can we find the right kind of accommodation options."

Ms Hatfield-Dodds says it is also important to make sure the right case workers are in place for traumatised and mentally ill people and that proper family support services are available.

The Government will release children and their families on a case by case basis, and Ms Hatfield-Dodds says the highest priority should go to people experiencing mental health problems.

But some say the new arrangements are still too onerous.

The Refugee Action Coalition's Ian Rintoul is not impressed that families will have to live in certain places and check in regularly with authorities.

"They will be designated people, and in some cases people won't be able to move out of a particular suburban house without being accompanied by a particular individual," he said.

"They will place curfews."

Some advocacy groups are dismayed that the Government has also announced it is building two new immigration detention centres in two states.

Amnesty is pleased families will have an opportunity to get on with their lives, but spokesman Graham Thom says the Government has missed an opportunity.

"The announcement that they were going to continue to maintain mandatory detention was really unfortunate," he said.

"This is something that's been criticised again and again by the international community, and it is an embarrassment.

"New detention centres are not the answer."

Concerns for children

The United Nations High Commission on Refugees has had long-standing concerns about the detention of children in Australia.

Its regional representative, Richard Towle, says yesterday's announcement is a positive step, but that Australia still needs to do more to improve its treatment of asylum seekers.

"We're not in favour of mandatory detention, if that is determined solely by the means of arrival, but we fully accept that a sovereign state like Australia has the right to detain people for an initial period to determine that they don't pose any real risk or threat to the community," he said.

"But what's very important is that those processes happen quickly and that people who clearly aren't a risk to the community are allowed out to continue with as much normalcy of their lives as they can.

"We'd also like to see perhaps more creative thinking around alternatives to detention for other people who also don't pose any threat to the community."

The non-government sector is urging the Immigration Department to implement the new changes as soon as possible.