I believe you can take the following steps:
1. Circulate an attendance and punctuality circular to all employees, mentioning the minimum working hours an employee has to complete. Also, point out the disciplinary action that will be taken in case of defaulters, such as memos, warning letters, or pay cuts.
2. The working hours (in/out time) can be monitored by installing a swipe card machine. Convince your management to install one by demonstrating the benefits of the system.
3. If a swipe card cannot be installed, keep an employee movement register in your reception area where employees have to enter in/enter out every time they leave the office.
4. At the end of the month, you can take necessary action against any defaulters.
I hope this helps.
Regards,
Prathiba