HONG KONG — HONG Kong tightened security in camps holding 64,000 Vietnamese "boat people" in anticipation of protests against a new agreement to resume its controversial, two-year-old forced-repatriation policy.Britain and Hong Kong announced an accord with Vietnam Oct. 21 under which a target group of more than 200 Vietnamese boat people will be sent home from Hong Kong in coming weeks. Yet negotiators failed to strike an accord that has been widely expected on returning all boat people denied refugee status in Hong Kong. Currently, 19,000 Vietnamese in the British colony have been "screened out" as non-refugees. That number is expected to rise to 50,000 as screening progresses. And boat people are still flooding in, with 3,000 arrivals in September. The Hong Kong government, depicting the Oct. 21 agreement as "the first stage," expressed a determination to reach an overall accord with Hanoi "well before the end of the year," says Refugee coordinator Clinton Leeks. Several problems, however, are obstructing such an agreement. Faced with the prospect of providing tens of thousands of migrants with jobs and housing, economically troubled Vietnam is negotiating with Britain and Hong Kong for more aid, Western diplomats say. "Vietnam is looking at the potential repatriation of up to 100,000 destitute people - that's pretty daunting," one diplomat says. So far, Britain has pledged some $5 million as part of a $100 million, two-and-a-half-year European Community assistance scheme to provide jobs, training, and low-interest credit for returned boat people. Moreover, Vietnam seeks to avoid condemnation by the United States and other countries if a large-scale mandatory repatriation drive should draw violent resistance from the boat people. International outrage caused Vietnam to suspend mandatory repatriations after a first group of 51 boat people were forcibly sent home in a pre-dawn action in December 1989. The small group targeted to be flown out in coming weeks is less likely to fight eviction or win international sympathy because it consists of "double-backers Vietnamese who returned to Hong Kong after leaving once under a voluntary repatriation scheme. The Bush Administration remains opposed to forced repatriation, but has expressed understanding for the "unique" problem of double-backers. Social workers in the camps predict that a colony-wide deportation would provoke more opposition, however. "The boat people will resist [mandatory repatriation], but on what scale I don't know," says International Social Services administrator Stephen Yau, who runs programs in the camps. Large protests erupted in the camps soon after Vietnam indicated in September that it had dropped its opposition to involuntary repatriations. Some of the 22,000 boat people at Whitehead, the largest of Hong Kong's prison-like detention centers, threatened to commit suicide rather than be forced to go home.