State social workers in Leominster say they are forced to strip-search children who are receiving social services when allegations or a history of physical abuse is at issue. Social worker Joseph Manna, who works in the Leominster office of the Department of Children and Families and also is a vice president of the union representing caseworkers, said some social workers have quit because of the strip-search policy. Cayenne Isaksen, a spokeswoman for DCF, said in a statement that workers view a child's body to document physical abuse if it is evident. She was not more specific. Manna said the policy of ''viewing bodies'' in the Leominster office requires social workers to view children who are not investigated for physical abuse. He said state law does not permit such searches.