SIX Vietnamese youths who were found cowering under a bunkbed in Whitehead detention camp's burnt-out Section Seven almost nine hours after a fire were being questioned by police last night. The six, hauled from their smoky hide-out by camp guards, were arrested with three others following an attempt to burn down the huts where riot police used tear-gas last week. A Correctional Services Department (CSD) spokesman said the nine, including a 13-year-old, had scaled double barbed-wire fences to set fire to blankets and clothing left by evacuated detainees on Thursday. Fire teams wearing breathing apparatus battled to put out the flames from about 3.30 am to 4.15 am. Soon after, CSD guards arrested two men in Section Seven and a third man later gave himself up. Yesterday afternoon clean-up staff were removing blankets, clothes and ashes from the blackened hut when they discovered the others. The pre-dawn arson raid set the scene for a tense weekend of demonstrations, intimidation and bravado in Hong Kong's detention camps. ''I think the motive was to show defiance,'' a CSD spokesman said. About 3,000 people demonstrated in Whitehead camp yesterday. Emotions were running high in Section Eight, where residents had watched police fire 250 rounds of tear gas to evacuate their fellow long-stayers and neighbours in Section Seven. Sources inside Whitehead said CSD staff ordered Vietnamese solidarity posters and flags to be torn from walls and bunks in an attempt to crush community spirit. The action has fuelled tension and led to the recall of United Nations staff working in the camp, the source said. Former Section Seven inmates, who spent the weekend at High Island detention centre, must answer a government ultimatum tomorrow demanding detainees sign up for ''voluntary repatriation'' or be shipped to Hong Kong's isolated camp for hard-liners at Chi Ma Wan. Camp insiders are predicting a ''summer of blood'' as the Government takes a tough line to display its authority and long-staying Vietnamese demonstrate angry defiance at moves to repatriate them. Hunger strikes continued yesterday as 68 High Island inmates, 58 from Tai A Chau and 35 from Whitehead refused food.