Bank claim based on a unregistered agreement

Without seeing the complete documents, and knowing the fact situation and on what basis the bank makes the claim etc. etc., it is not possible to answer your query "Does the bank claim any right on my property for a a loan given based on a unregisterd agreement?"

As regards your query "What will be my course of action?",  you will be well advised to get in touch with a local lawyer, show the documents in your possession, discuss the matter in detail and then take appropriate steps.

'Buyer Beware' applies to property deals.

It shall be appropriate to get proper legal opinion from a very able LOCAL senior counsel of unshakable repute and integrity specializing in revenue/property/civil/DRT matters and well versed with LOCAL applicable rules/laws and having successful track record…. and worth his/her salt , before signing or making payment.

This may cost some FEE but can defend long term interest and hard earned monies.

In the said year at the Location find out if IT was mandatory to register the agreement between promoter and said person.

Before the lender bank proceeds further for (Symbolic) possession or takes, approach a very able counsel ASAP.