A further four asylum-seekers who escaped from the Woomera detention centre in South Australia have been caught, according to police reports.

The three men and a boy were detained in the mining town of Coober Pedy, more than 300 kilometres (180 miles) to the north of Woomera, following a tip-off from members of the public.

Five others were captured earlier, but more than 20 people remain at large after the mass breakout on Friday morning - the second such incident at the detention centre this year.

As police and dogs with air support comb the surrounding desert, the government has warned it will prosecute anyone on the outside who helped them escape.

Most of those who escaped were Afghans, along with some Iranians and an Iraqi man, all of whom are understood to have had their applications for refugee status turned down.

Inquiry launched

Immigration Minister Philip Ruddock said 15 asylum-seekers broke out initially while another 20 took advantage of the confusion and fled into the desert surrounding the camp.

Vehicles leaving the area are being searched

The BBC's Sydney correspondent Dominic Hughes says an inquiry has been launched into how a group of protesters from outside the camp were able to cut a hole in the perimeter fence and enable the detainees to escape.

Our correspondent says that far from being an organised break-out, it seems to have been a spontaneous action.

And, even more embarrassing for the Immigration Department, there are reports that the private security firm contracted to run the centre only had three staff on duty at the time of the incident.

'Arrogance'

According to a report in the Sydney Morning Herald daily South Australia's Police Minister, Pat Conlon, accused Mr Ruddock of arrogance for failing to resolve the problems at Woomera.

"We have had detention centres in Australia since the later 1980s and none of them have these ongoing problems," he was quoted as saying.

The United Nations has criticised conditions at the remote desert camp, which has been the scene of riots, attempted suicides and a previous mass breakout.

Woomera holds about 210 migrants, almost all of whom have had their claims for asylum in Australia rejected, though about half still have legal appeals pending.

Responsibility claim

Though detained behind wire fences, people are free within the centre and not locked into their huts at night.

Witnesses said the latest breakout happened after a group of protesters arrived at the compound in vans and cars, blowing their horns and behaving like drunks before tearing down the fence.

A pro-refugee group contacted Australian news organisations to claim responsibility for the breakout.