Landlord demanding extra rent amount not mentioned in agreement, how to proceed?

I rent an apartment in Mumbai, and suddenly my landlord is demanding an additional ₹10,000 as rent for this month, claiming unexpected expenses. However, the rental agreement clearly states the fixed monthly rent. I am unsure how to handle this situation. Can he legally demand more money than agreed? Should I refuse to pay and what action can he take against me? I need advice before things escalate.