A consortium led by RBS has confirmed that it intends to make a takeover offer for the Dutch bank ABN Amro.
The consortium says its offer will be worth more than Barclays'
RBS and allies Fortis and Santander say their offer represents "higher value" for ABN's shareholders compared with the recommended offer from Barclays.
Barclays is offering about £45bn in shares for the Dutch lender, but on Thursday ABN's shareholders told the bank to sell to the highest bidder.
RBS, Belgium's Fortis and Spain's Santander have yet to reveal a price.
The consortium called on ABN's board to discuss its proposals as soon as possible.
It added that under Dutch takeover regulations it is not allowed to give details of the offer price indicated in its note to the ABN board.
Earlier this week, the consortium said it planned to offer 72.2bn euros ($98.2bn; £49.4bn) or 39 euros a share for ABN Amro.
The announcement was prompted by Thursday's unusually lively ABN Amro Annual General Meeting.
Sixty-eight percent of ABN shareholders supported a resolution calling for the company to "sell, spin-off or merge some or all of the major businesses".
James Buckley from the banking consultancy Lafferty Group said: "The consortium has been emboldened by what happened yesterday to reveal its intention to make an offer - we expect the price will remain at 39 euros per share."
The arguments at the shareholders' meeting centred on ABN Amro's decision to sell its US unit LaSalle to Bank of America for $21bn (£10.6bn).
The offer by the RBS-led consortium is dependant on the reversal of the sale of LaSalle.
The Dutch shareholders group VEB says it has filed a suit to prevent the sale going ahead.
VEB chief Peter de Vries said: "As far as we're concerned [the LaSalle sale] is a trick to prevent ABN from being taken over by a party other than Barclays."
Mr de Vries made his case forcefully at Thursday's AGM, at one point being escorted from the stage by security guards after attempting to seize a microphone.
VEB says the sale should have been subject to shareholder approval, and has filed a request for an injunction with the Amsterdam District Court.
Mr Buckley says that the fate of LaSalle is central to who eventually wins the takeover battle.
"If ABN Amro is able to sell to Bank of America then Barclays is favourite, if not then the rival consortium will be in a stronger position," he said.