Camps have been criticised by human rights groups

Immigration Minister Philip Ruddock said the decision was partly due to the falling number of boat people trying to get Australia.

Mr Ruddock said that no boat had reached Australia since last August, when the government began a new crackdown on immigrants.

Since August, navy patrols have either forced unwanted boats into international waters or diverted the migrants to temporary camps in the South Pacific.

Previously, all illegal immigrants were sent to one of five centres in Australia. The camps have been condemned by the United Nations and human rights groups, especially for holding women and children, some of whom have been in detention for more than three years.

About 10 detainees are still missing following a break-out from Woomera nearly two weeks ago during protests over the length of time taken to process asylum claims.

'Worst camp'

Woomera, a former missile testing base in the remote southern Australia desert, is the biggest camp, but currently holds just 300 people out of a capacity of 2,000.

The major horror of Woomera, which is indefinite detention, is still there

Natasha Verco, refugee group

With no new arrivals, the population dwindles every week as asylum claims are processed and migrants either deported or released.

Last year a parliamentary committee singled out Woomera as the worst camp for human rights abuses.

A spokeswoman for the national refugee advocacy group welcomed the news that the camp was being scaled down, but said it should be closed altogether.

"The major horror of Woomera, which is indefinite detention, is still there," Natasha Verco said.

New camp at Baxter

Opening next year 1,200 places Two people per room En-suite facilities Less razor-wire Source: Immigration Dept

Mr Ruddock said Woomera, and the camp being closed - Curtin, in Western Australia - were getting old and were no longer suitable.

The new camps would be smaller and provide "higher levels of amenity and security," he said.

A new mainland camp, Baxter Immigration Reception and Processing Centre, near the remote mining town of Port Augusta in South Australia, will be ready next year, Mr Ruddock said.

The government is also building a new camp on Australia's remote Christmas Island in the Indian Ocean, which will have about 1,000 places by the end of the year.

Under Australia's 'Pacific Solution', the island nations of Nauru and Papua New Guinea take in asylum seekers in exchange for aid. The migrants are housed in makeshift camps while their asylum claims are processed.