Updated

ADELAIDE, Australia (AP) — The U.N. refugee agency expressed concern Monday that Australia is using holding newly arrived asylum-seekers in detention centers.

The government suspended refugee applications from Afghans and Sri Lankans on April 9, saying the situations in those countries had improved.

The new policy says the suspensions will be reassessed in three to six months. Until then, new asylum-seekers will be housed in detention centers. The government has already been forced to open new centers to cope with an overflow of arrivals.

But the U.N. said Monday there should be alternatives to detention for those who posed no security risk.

"The combination of mandatory detention, suspension of asylum claims and the geographical isolation of detention facilities ... all without any effective judicial oversight — is a deeply troubling set of factors," said Richard Towle of the U.N. refugee agency.

Detention is likely to have a negative impact on the physical and mental health of asylum-seekers, particularly those who have been tortured or traumatized before arriving in Australia, the U.N. said.

It particularly criticized the remote location of a new detention center to be opened at Curtin air force base in the state of Western Australia. The federal government announced Sunday that the facility, which had been used for the same purpose under the previous administration, would house up to 300 Sri Lankan and Afghan asylum-seekers whose applications were on hold.

The government is struggling to cope with illegal boatloads of asylum-seekers who have filled an offshore detention center and fueled a political debate over immigration policies.

The current government relaxed immigration regulations in 2008, reducing the time would-be refugees spend in detention before their applications are processed and dropping a requirement that they must renew visas every five years.

The opposition claims that those changes led to the tenfold increase in illegal boat people in 2009 over the previous year. They say the illegal arrivals drain money and resources and that they should apply through the established U.N. refugee process.