THE first break in solidarity among Vietnamese hunger strikers came at High Island detention centre last night when all but 24 of the 2,600 detainees agreed to resume eating. The change of heart, which came one hour after the normal dinner time of 5 pm, forced Correctional Services Department (CSD) cooks to swing into action and begin preparing meals. A senior CSD officer said the decision followed ''intensive counselling'' yesterday by CSD staff in meetings with Vietnamese representatives. The move was pre-empted earlier in the day by three people who requested food and protective custody. The entire High Island camp population of 2,600 had been refusing food for the past few days, and in an effort to get people to eat, the CSD had been telling detainees that special ''safe'' accommodation would be provided for anyone wishing to eat. It is believed that many people had been eating supplies of unofficial food, but this was fast running out. The Post reported yesterday that five men at Whitehead were transferred to Upper Chi Ma Wan - a camp for troublemakers - after complaints were received that they had threatened the safety of fellow Vietnamese refusing to join the hunger strike. However, Whitehead detainees claimed yesterday that the men were not making any threats and that in fact they were being persecuted by the CSD for their roles in the hunger strikes. Hunger strikes and demonstrations have been conducted in the three main Vietnamese detention centres since early last month. In general, they are protesting against the refugee determination procedure and moves to repatriate them all by the end of 1995. Yesterday, the United Nations High Commissioner for Refugees chief of mission, Jahanshah Assadi, met representatives from Whitehead. Mr Assadi said the talks had been both constructive and instructive, with both sides able to explain their points of view. He said he appealed to the group to call off the strike.