Yours is a KPO hence will not b e covered under Factories Act. Your organisation will be covered under Shops and Establsihments act
Hence this may vary from State to State.
In Tamilnadu, Shops and Establishment Act provides for maximum work of 10 hours in a day including Over Time in Section14. This means no person shall be engaged on Over Time for more than 2 hours on any days in Tamilnadu in KPOs and BPOs and other establishments.
there is also another celing of 54 hours of work in a week. Assume you work for 6 days a week and eight hours a day.
This implies that an employee works for 48 hours. Then in that week, he can be engaged on over time for six hours spread of six days ( One hour a day) or three days at 2 hours a day.
However if an emnployee is on leave , then he can be engaged on OT for 2 hours a day for five days.
Simple answer to your question in Tamilnadu:
Maximum of two hours in any day as OT. Ref to relevat provisions of Shops and Establishments Act in respective States
Sivasankaran