A FORMAL offer is on the table for Castlemartin - Tony O'Reilly's period mansion house and 750-acre stud farm in Kildare, according to London based Knight Frank estate agency.
At the same time the agency has also confirmed that it will seeking "expressions of interest" from all other interested parties by 12 noon tomorrow.
The property was recently placed on the market for more than €30m.
While not a "best and final offer" process, calling in expressions of interest is a method of cutting down the field to ringfence serious parties.
It usually represents a move into the endgame of a sales campaign.
It is not usual for any estate agency to call in the other parties unless the bid on the table is bona fides and acceptable.
The spokesman for Knight Frank said: "A serious bid is on the table and we now need to push this process forward."
The London-based firm, which specialises in selling top end luxury homes in an international market, would not say whether the offer was from an Irish or non national interest.
The period house and 750 acres is being sold on the instructions of AIB, to whom Mr O'Reilly's companies owe over €22m. The 1720 built mansion has eight bedrooms and spans 26,000 sqm. The complex also has a swimming pool and an ice-house.
It was long believed that businessman JP McManus was likely to make the running for the O'Reilly property given that he has expressed interest in the property in the past.
However it was recently reported that the equestrian entrepreneur has offered €30m for Adare Manor and market sources agree this may rule him out of a deal.