An employer given salary hike to all it’s employees uniformly based on the salary benchmarking and similar industry practice for retention of employees, then by a common office circular put a condition that if any employee leaves organisation with in a period of one year from the date of salary revision the difference incremented amount will be recovered from Full & final settlement of the concern employee.

Whether it is legal to recover the salary once paid to employee by giving the reference of the circular. In this case no formal agreement was executed between employee and employer or in other word employee has not given any acknowledgment on the condition / circular. Please share your input also share the legal provision avilable.