The Royal Bank of Scotland-led consortium trying to scupper Barclays' acquisition of ABN Amro in the world's biggest banking takeover battle is resisting the Dutch group's efforts to secure a promise that it will not take its bid hostile.

RBS, Fortis Bank of Belgium and Santander of Spain today revealed the confidentiality documents they received this afternoon from ABN Amro, which they must sign to gain extra access to the Dutch bank's books, contain a standstill clause barring them from making an unsolicited or hostile offer for the bank for a year.