Barclays has drawn up contingency plans to restructure its all-share offer for ABN Amro with a significant cash sweetener, in case it is forced into a full-blown battle for control of the Dutch lender.

The British bank recognises that, unless legal disputes run in its favour, it will need to improve its €65bn ($86bn) offer if it is to trump the Royal Bank of Scotland-led consortium. But it is mindful of warnings from shareholders not to raise its price.