The board of Alliance & Leicester has scrapped merger discussions with Bank of Ireland.
The high level merger talks collapsed amid accusations the Irish reneged on the original deal.
A&L says it pulled the plug on the £11.5bn merger talks when the Bank of Ireland tried to renegotiate several key issues which had already been agreed.
The Bank of Ireland denies any written agreements had been made but A&L claims the Irish tried to change seven clauses that had been previously agreed.
Alliance & Leicester Group chief executive John Windeler says: "The board unanimously believed that under the terms originally proposed a merger would have been a strategic move which would have brought shareholders a significant increase in long term value.
"In the course of negotiations it has become clear that despite the acceptance of the agreement which formed the basis of the joint announcement on May 24 those terms are no longer acceptable to the Bank of Ireland. As a result they have requested changes to key items which had previously been agreed.