By Amy-Jo Crowley and Andres Gonzalez

LONDON/MADRID (Reuters) -Santander is among bidders that submitted a binding offer for Spanish lender Sabadell's British unit TSB, two sources with knowledge of the matter told Reuters.

The offer would value the British bank at more than 2.3 billion pounds ($3.15 billion), one of the people said. Sabadell may hold a board meeting as soon as Tuesday to decide on whether to proceed and if so which bid will win, the person said.

The people spoke on condition of anonymity because the process is private. Santander and Sabadell declined to comment. Other potential bidders include Barclays, Bloomberg previously reported, which Barclays has not commented on. Reuters could not establish who the other bidders were.

The move on TSB, which has the seventh largest branch network among UK banks, comes as Sabadell tries to ward off being taken over by rival BBVA. Analysts say the process of selling TSB could be a defensive move to keep its bigger peer at bay.

Sabadell said earlier this month it had received unsolicited interest in TSB. Any negotiations over a sale of TSB will require Sabadell to seek permission from its shareholders. The process is further complicated by an impending decision by BBVA on whether to proceed with its offer for Sabadell, after the Spanish government this month limited a full merger for at least three years. Should any deal for TSB eventually materialise it would represent the latest step in the consolidation of the British banking landscape. Nationwide Building Society agreed to buy Virgin Money last year in a  2.9-billion-pound  all-cash deal, while Barclays also acquired the banking operations of supermarket group Tesco for about 600 million pounds. The buyer of TSB would add assets of 46 billion pounds, predominantly comprised of mortgages, and customer deposits of around 35 billion pounds.

(Reporting by Amy-Jo Crowley and Andres Gonzales in London. Additional reporting and writing Jesus Aguado in Madrid. Editing by Anousha Sakoui and Susan Fenton)