Though it is an international BPO, since it is loacted in Delhi, it will be governed by Indian Laws. A BPO is an establishment within the meaning of Shops and Establishments Act which every State has enacted for establishments located in it's State. In your case it is Delhi Shops Act that is applicable. The Shops Act provides for leave to be granted to the employees working in establishments covered by it. The Shops Act of some states have granted exemptions from the applicability of Shops Act to I.T and ITES establishments with regard to working hours and women employees or leave provisions. You need to go through the Delhi Shops Act to frame your own leave policy keeping in view the exemptions and the minimum benefits provided by the said Act.