Only formals, blazer/suit, tie, and be very well groomed as if you are going to give an interview of your life. Treat it as if your are trying for a job in an MNC.
rightly said .... no casuals ....
however you could be comfortably dressed in a proper full sleeve shirt with tie etc ....
i dont think need for blazer or suit ..... however best of luck...
regards.
kash.