Thirty asylum-seekers are still on the run in South Australia after activists allegedly helped stage a mass escape from the Woomera detention centre.

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.

This escape was an organised criminal action and involved detainees whose refugee applications have been refused

Immigration Department spokesman

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.

Five escapees have now been recaptured while another 10 have been sighted, and three outside activists have also been arrested.

Police said the 35 men and boys, who are all thought to be Afghans, escaped at around midnight local time (1530 GMT Thursday) when a vehicle carrying protesters approached the former missile-testing base.

The migrants escaped through a hole in the fence that had been cut from the outside using a bolt-cutter.

Prime Minister John Howard has said anyone who helped them will be pursued and prosecuted.

Harsh conditions

Roadblocks have been set up around the detention centre 450km (280 miles) north of Adelaide and police have been carrying out house-to-house searches.

The authorities said the harsh conditions would make it hard for anyone to get far without a vehicle.

Of the five migrants recaptured, one was taken in Woomera and four in Coober Pedy, 300km away.

The 10 escapees sighted are expected to be caught shortly, officials said.

The raid came as the largest hunger strike at the camp since January entered its fifth day and just hours after four detainees stitched their lips together in protest.

Fence destroyed

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

Witnesses said the 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.

There was a mass break-out at Woomera in March

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.

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

Mr Howard condemned those who helped the escape.

"It is inflammatory and unhelpful and potentially criminal... for people to assist in a breakout," he said.

'No policy change'

He added that Australia's tough immigration policies would stay and were working.

The latest hunger strike at Australia's most notorious detention camp has been joined by about 160 of the detainees - said to include children and a pregnant woman - who are refusing all food and water.

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 is one of five mainland camps where hundreds of illegal immigrants including children are locked up while their asylum claims are processed.