THE Government has told striking social work assistants they will not get more pay because their argument lacks ''indisputable logic''. The Director of Social Welfare, Ian Strachan, said the Government would not be held to ransom by industrial action and would pay no heed to the protesters' one-month settlement deadline. He called for the strike to be called off and for differences to be settled around the negotiating table. ''We are not going to achieve anything in this exercise by confrontation. The only way to achieve anything is by negotiation,'' he said. ''The door remains open for negotiation on our side.'' A task group has been set up to look into the pay claim. But Mr Strachan indicated that no matter how much discussion took place, the social work assistants' case was too weak. ''The only way [they will win a better deal] is to provide indisputable logic [that they deserve more], and so far this has not been produced,'' he said. Members of the social work assistant branch of the Hong Kong Chinese Civil Servants' Association are refusing to work because they believe they should be higher in the pay scale than senior welfare workers, They began a three-day sit-in at more than a dozen centres - including juvenile correction institutes, rehabilitation centres and homes for the elderly - at midnight on Sunday. The branch claimed all its 251 members out of 437 social work assistants were taking part in the dispute. But Mr Strachan said only about 120 people were involved, 20 less than on Monday. He admitted the industrial action had affected work at the centres, without giving details. Redeployment from other areas of the department meant disruptions had been kept to a minimum, he said. But there were claims from within the branch that juveniles has been kept indoors all day and many had been offered incentives, such as extra food, to stay quiet until the dispute was over. Social work assistants want to leapfrog senior welfare workers in the pay scale, boosting their minimum monthly salary from $18,205 to $20,905, compared to a monthly minimum of $19,965 for senior welfare workers. Social work assistant branch chairman Lai Wing-shing said the department's offer to set up a task group was a stalling tactic, and threatened further industrial action unless their claim was approved within a month. ''Social work assistants are better qualified than senior welfare workers and in every other government department that means they get better pay,'' he said. Mr Strachan said the pay structure was revised in the 1980s and he believed it to be correct.