A consortium led by Royal Bank of Scotland (RBS) said on Friday it had formally launched its 71.1 billion euro ($98.2 billion) bid for Dutch bank ABN AMRO (AAH) as it attempts to beat rival suitor Barclays (BARC) to the biggest ever bank takeover.

The consortium, which also includes Spain's Santander (SAN) and Belgian-Dutch group Fortis (FOR), said the initial offer period would run from July 23 until October 5.

The consortium said its offer is equivalent to 38.40 euros per ABN share, of which the cash component is 93 percent.

The consortium's offer is about 10 percent higher than an all-share offer from Barclays, currently worth about 35 euros per ABN share.

ABN's boards have recommended Barclays' offer, but ABN said on Wednesday it planned to discuss the revised offer with both the consortium members and Barclays, prompting speculation it could switch its recommendation.

If ABN chose to switch, it is obliged to notify Barclays, which would have five days to respond, according to an SEC filing of their original deal.

Barclays said on Thursday it may sweeten its offer by adding cash, but analysts said it is unlikely to be able to outbid the consortium and some of its investors have urged it not to get into a bidding battle.

RBS has already cut the revenue benefits it expects to achieve from the deal after a Dutch court allowed ABN to sell its U.S. business LaSalle Bank to Bank of America (BAC), which RBS had originally wanted to keep as part of the deal.

Both bids would rank as the world's biggest bank takeover.

The consortium plans to break up ABN, which has more than 4,500 branches across 53 countries.

RBS will get ABN's wholesale and investment banking unit and its Asian businesses; Santander will buy ABN's Italian bank Antonveneta and its Brazilian bank; and Fortis will get ABN's Dutch operation to create a dominant Benelux retail bank, and also its wealth and asset management business.

ABN's shares have jumped more than 45 percent since a hedge fund investor urged the bank in February to break up or sell the bank.