Dear Prabhat ji,
With due respect to you, I would like to differ with you on your statement - No one is eligible for any sort of leave while on probation or training or internship.
Internship is not an employment as I said in my earlier post. Any kind of leave to interns is totally depends upon the arrangement between the interns, the college or the institute of which the interns is a student & the company.
As regards to probationer or trainee, they are the employees of the company and they are governed by S.O. / Law relating to service conditions such as FA, S&E Act as applicable / service rules or policy formulated by the company in accordance with law. The privilege leave is earned by an employee from his day one of employment however he is permitted avail it as per company rules & regulations, generally in next year. Even casual leave is credited in the account of employee from his first day of employment onwards, generally. No Act says that an employee is not eligible to any kind of leave during probation or trainee period, to my knowledge.