Dear DsDeep,
Whatever might be your compulsions, it's not legally valid to restrict anybody to avail or not to avail leave. Instead you can issue a general circular/mail advising
"everybody to avail leave only after obtaining prior approval of competent authority except on extreme unavoidable circumstances like accident, ill health etc. regularisation of which is within the discretion of management. And non adherence of this stipulation will attract action as indiscipline"
kumar.s.