Dear Sridhar,
Annual increment is an internal matter of the company and it is not covered under the provisions of the labour laws.
You may "request" your company to consider your name for the annual increment but it is not advisable to "fight" with them. If you have resigned, then you must be under the notice period. These are not the days where you can antagonise the company's officials. Yes, the mention of the higher remuneration on the last payslip always matters. However, raise this issue politely. No superiors or someone from HR can be rubbed the wrong way.
General comments: - When the company is due to release the annual increment and during this period, if some employee resigns then should the company withhold the annual increment of that employee? This is a question to moot. If the company wishes that their ex-employees talk positively about the company, then naturally they will not bother for forgoing a few thousand Rupees. However, if the cost-consciousness outweighs the brand image of the company in the job market, they will resort to this kind of thing.
Thanks,
Dinesh Divekar