Is it legal for my landlord to increase rent without notice?

I've been living in a rented apartment in Hyderabad for the past two years. Suddenly, my landlord has demanded a 25% increase in rent starting next month. We didn't discuss this change, nor did I receive any prior notice. This increase will make it difficult for me to manage my finances. Is he allowed to do this without any formal notice or agreement? What should be my next steps legally?