Is my landlord allowed to increase rent by 20% without notice in Delhi?

Hi, I'm feeling quite anxious. I've been living in the same rented apartment in Delhi for the past 2 years. My landlord suddenly informed me that the rent would increase by 20% from next month, without any prior notice or discussion. Our original agreement mentioned rent revisions would occur annually, but this sudden hike feels unfair. I haven't signed any new agreement yet. Can he legally enforce this increase without giving proper notice? What are my rights as a tenant to negotiate or challenge this unexpected hike?