''The climate in Section 7 [which was the target of Thursday's raid] had the potential to be explosive. It was at the point where it was in the public interest and the interest of innocent people for the Government to take control,'' he said.

The inmates had staged protests and hunger strikes in recent weeks that escalated to threats to set fire to themselves, their huts and their children, and to meet any attempts to move them with human barriers of children and badly scarred victims of the 1992 Sek Kong fire, he said.

Most had been in the section since 1989 and had witnessed a number of disturbances, including stomach slashing and riots.

''You have a pattern of extreme behaviour over time since 1990, be they slashings, suicides, attempted immolations or riots. Plus the community had organised itself in a very negative way,'' he said.

''Given the previous behaviour and the threats and the climate in the camp, the Government couldn't ignore them. Their actions were justified.'' Mr Torgrimson was working with the aid agency Community and Family Services International when Vietnamese in Section 7 slashed their stomachs in 1990, some in front of him, in a protest against repatriation.

During his two-year stint, there also was a Whitehead inmate who set fire to himself and suffered third-degree burns and some who committed suicide saying they could not face repatriation to Vietnam.

Riots have been a fairly regular feature of camp life, the worst culminating in the 1992 fire at Sek Kong camp in which 24 people died after being barricaded in their blazing hut by other Vietnamese.

Mr Torgrimson said: ''Certainly the potential for a Sek Kong-like incident was there, especially with a minority leadership dealing from an extreme position. They were not backing down, they were not in a negotiating mood.'' He said extremist leaders had gained control in the camps because people had little hope and they were intimidated from breaking ranks by peer pressure and extortion.

Governor Chris Patten yesterday congratulated the Correctional Services Department (CSD) and police for their handling of the ''difficult problem'' at Whitehead.

''We cannot have a position in which there are no-go areas in camps and in which sensible arrangements are blocked by the behaviour of a minority,'' Mr Patten said.

''We will continue to run the camps as fairly and as efficiently as possible but we will decide what is efficient and fair in conjunction with the UNHCR [United Nations High Commissioner for Refugees],'' he said from London.

The next government deportation flight will be filled with ''hardcore'' members of the 1,500-strong group of Vietnamese removed from Section 7.

Senior government sources confirmed yesterday that an orderly repatriation programme flight was scheduled this month and the bulk of the people forced to board the aircraft would be chosen from the former Section 7 inmates who were said to be the ringleaders behind months of hunger strikes and demonstrations.

The CSD yesterday confirmed a report in the Post that the bulk of the 1,500 people moved from Whitehead would be placed in the tough Chi Ma Wan prison on Lantau Island.

Many of them will be placed in Lower Chi Ma Wan where a group of ex-China Vietnamese illegal immigrants are being held. The balance will be placed in Upper Chi Ma Wan which holds about 80 Vietnamese.

The move to Chi Ma Wan will take place in about two weeks. Any of the group who choose to sign up for the voluntary repatriation programme will be moved to the departure centre at Whitehead.

Thursday's operation has also prompted Sha Tin District Board members to ask why villagers living near Whitehead had waves of tear-gas flooding through their homes.

Meanwhile, protests in the territory's three main Vietnamese detention centres were stepped up yesterday in the wake of Thursday's military-style operation at Whitehead.

Extra teams of CSD staff were posted to High Island but have been ordered to maintain a low profile so as not to aggravate the tensions in the camp.

About 700 people staged a peaceful protest at High Island yesterday morning and a group of 600 launched an afternoon demonstration. Meanwhile 110 people continued a hunger strike which began in February at High Island.

At Whitehead, about 3,000 people gathered in several compounds when a commercial helicopter was seen hovering over the camp at about 1.40 pm, later developing into a small demonstration.

At Tai A Chau 85 people were listed as refusing food yesterday and two hunger strikers were admitted to the camp clinic.