Image copyright AP Image caption More than 1,000 children are currently in immigration detention - both in Australia and offshore

Australia's Human Rights Commission has announced an inquiry into the mandatory detention of children seeking asylum.

The inquiry would focus on the well-being, health and development of the detained children, AHRC President Gillian Triggs said.

More than 1,000 children are currently in Australia's immigration detention facilities, the AHRC said.

This included more than 100 in Nauru - the offshore centre condemned by the UN and rights groups for poor conditions.

"These are children that, among other things, have been denied freedom of movement, many of whom are spending important developmental years of their lives living behind wire in highly stressful environments," Prof Triggs said in a statement.

Australia and asylum Asylum seekers - mainly from Afghanistan, Sri Lanka, Iraq and Iran - travel to Australia's Christmas Island on rickety boats from Indonesia

The number of boats rose sharply in 2012 and the beginning of 2013, and dozens of people have died making the journey

The Labor government reintroduced offshore processing in Nauru and Papua New Guinea - conditions in its detention camps there have been condemned by UN agencies and rights groups

The Tony Abbott-led Liberal-National coalition government, elected in September 2013, introduced "Operation Sovereign Borders", putting the military in control of asylum operations

In January reports emerged of Australian navy vessels turning asylum boats back to Indonesia; Australia then apologised for multiple violations of Indonesia's territorial waters by navy vessels on asylum operations

Relatively small numbers of asylum seekers are involved: UNHCR's Asylum Trends 2012 report said Australia received only 3% of global asylum applications in 2012

The commission's first report on the subject, in 2004, found that mandatory detention of children of asylum-seekers was inconsistent with Australia's human rights obligations, and that long-term detention placed children "at high risk of serious mental harm".

In an interview with the Australian Broadcasting Corporation, Ms Triggs highlighted a lack of co-operation from the immigration department.

"I think I'd have to say over the last few months, we've had minimal co-operation in relation to the kinds of details that I need to know, particularly mental health, self-harm and the processes for those that are transferred," she said.

"In particular, we'd like to understand more about the mental health of these children. The instances of self-harm, how they're being treated when they're manifesting conditions of extreme anxiety."

Ms Triggs said the AHRC did not oppose detention for an appropriate period to establish the identity and health of a child.

"However, we are concerned that when the time moves beyond three to four months - to six, to 12, to 15 months - the likelihood is that we will be finding that there are breaches of international law."

'Chaotic mess'

Immigration Minister Scott Morrison said officials would co-operate with the inquiry.

"But the reason there are children in detention is because over 50,000 turned up on illegal boats on Labor's watch so we're dealing with Labor's chaotic mess here,'' he told local radio.

Those who arrive in Australia by boat to seek asylum are placed in mandatory immigration detention. The number of boat arrivals rose sharply in 2012 and the first half of 2013.

In response, Australia re-opened offshore processing camps in Nauru, a tiny Pacific island, and in Papua New Guinea. The previous Labor government also introduced the deterrent "PNG solution" - an agreement whereby those found to be refugees would be settled in PNG, not Australia.

Under the new Liberal-National coalition government, "Operation Sovereign Borders" - putting the military in charge of anti-people-smuggling efforts - has been introduced.

Reports suggest Australia has been turning asylum boats back to Indonesia - and in January, Australia apologised for "inadvertently" violating Indonesia's territorial waters on multiple occasions.

The government is strictly controlling the release of information around its asylum policy, prompting critics to accuse it of excessive secrecy. The government says it has drastically cut the number of boats arriving in Australia.

Rights groups and UN agencies, meanwhile, continue to criticise conditions in Australia's offshore processing centres and to question whether its current asylum strategy violates its international obligations.

The inquiry could be concluded before the end of the year, Ms Triggs said.