A Dutch court will rule on Thursday whether to uphold a shareholder petition to halt the sale by ABN Amro of LaSalle, its US lender, a move that would throw wide open the increasingly acrimonious battle for the Dutch lender.

Such a decision could leave ABN open to a damages claim from Bank of America, to which it has agreed to sell LaSalle for $21bn unless there is a higher offer by midnight Friday that BoA is unwilling to match.