Legality of additional rental brokerage demanded by broker

Hi CA Club members,

Please help me clarifying/suggesting on the following issue/problem I am currently facing 

I had rented an apartment in Nov-2014 through a property agent and had paid one month rent brokerage to him at the time of occupying the flat. And a formal rental agreement for one year was signed between me and the owner. After 1.5 years ( in 2016) the agent called up and asked to pay again one month rental brokerage for the second year stay. At the time of renting the apartment, the broker did not tell me that he will charge me again one month rental brokerage for second and subsequent years if I continue to stay in the same flat. Now he is putting pressure to pay the additional brokerage which was not discussed or agreed upon at the time of renting the apartment.

Since the agreement for rent  has lapsed , my flat owner wants to sign new rent agreement which I am fine with it. But the broker is insisting that I pay one month rental brokerage to him for renewing the lease.

My question is the demand for rental brokerage by the broker for subsequent years renewal between tenant and owner is legally valid and that too he did not specify this demand at the time of renting the flat through him.

Please let me know how to go about dealing with this particular issue.

Thanks

Josh