Royal Bank of Scotland, in partnership with Santander of Spain and Fortis of Belgium, are bidding around 13% more for ABN Amro than was offered by Barclays in an apparent merger agreement.

Shareholders of ABN, a Dutch group, were offered 70% in cash and 30% in RBS shares. Analysts expect ABN’s board to regard the approach led by RBS as hostile, and to try to resist it.

The Dutch bank regulator has signalled that it is uncomfortable about dismantling ABN, and politicians in The Netherlands are thought likely to support its views.

Any deal would need regulatory approval in many countries, which would delay the outcome even if there were agreement among the parties.