Hi, I hope not all the employees are requesting leave on ill health grounds. In any organization, depending on the size, mostly 5-7% of employees will be on leave on a daily basis, either on pre-approved leave or unplanned leave. So, wherever you feel that the reason for leave is not genuine, you may insist on medical proof. You may pass on an advisory communication to all employees, and a warning is not required. You cannot warn everyone just because some x or y is availing unplanned leaves.
Dear Employees,
Of late, it is observed that some of the employees are availing unplanned leaves with last-minute information, which is not a good practice. Planned leave/advanced leave information would be very useful for your immediate supervisor to plan their work, and unplanned leaves affect our work schedule and planning. We hereby advise all employees to plan their leaves well in advance, and in the case of any unplanned leave, the same has to be justified with proper medical proof. In the absence of the submission of proper medical proof, the leave of absence will be considered as leave without pay. All your cooperation is solicited.
Regards