The Royal Bank of Scotland Group and two other European banks made a formal $95.6 billion bid today for ABN Amro, the Dutch bank at the center of a bidding war with Barclays in the richest banking takeover.

The bidders addressed concerns of shareholders by planning to set aside money for a possible lawsuit over the sale of LaSalle Bank, ABN Amro’s American unit, but have yet to solve some regulatory and legal uncertainties.

Royal Bank of Scotland and its two partners, Banco Santander Central Hispano of Spain and Fortis, the Belgian financial-services group, offered 71.1 billion euros for ABN Amro, or 38.40 euros for each ABN share.

About 79 percent of the offer, more than investors previously expected, will be paid in cash and the rest in Royal Bank of Scotland shares. An earlier offer from Barclays, the British bank, is worth 34.87 euros a share.

“The offer is now certainly more transparent than it used to be and the cash component is higher than we expected, which is positive, but uncertainties remain,” said Ton Gietman, an analyst at Petercam in Amsterdam.

The group of three banks provided more details about how it planned to break up ABN and how it wanted to finance the bid. It also said that it planned to set aside about 1.85 billion euros of the bid “pending resolution of the LaSalle situation” but still needed approvals from regulators, ABN’s shareholders and those of all three bidding banks.

ABN Amro shares fell 29 cents, or 0.8 percent, to 35.81 euros in Amsterdam on Tuesday, showing some investors remained skeptical about the success of the consortium’s bid. Which bid will win partly depends on a ruling by the Dutch Supreme Court expected this summer on whether the agreed sale of LaSalle by ABN Amro to Bank of America can go ahead.

This month, a Dutch court earlier this year halted the sale of LaSalle Bank — which ABN had agreed to sell to Bank of America for $21 billion as part of the proposed Barclays deal — because ABN had not sought shareholder approval. ABN appealed the ruling, and a court decision is pending.

The Barclays bid for ABN Amro hinges on the successful sale of LaSalle, while the Royal Bank of Scotland Group said its bid was contingent on the LaSalle sale being reversed.

Bank of America said earlier that it would sue ABN if it broke the purchasing agreement for LaSalle, adding a legal risk to the rival bid.

Fred Goodwin, Royal Bank of Scotland chief executive, said Tuesday at a press conference in London that he had held talks with Bank of America about finding a solution for LaSalle. The talks were “amicable” but ended recently without an agreement and Mr. Goodwin said he remained open for new discussions.

Some analysts suggested a split of LaSalle between Royal Bank of Scotland and Bank of America would be the most desired outcome of the takeover battle.

It would guarantee Bank of America that it would not walk away empty handed should the Dutch court block the LaSalle agreement and for the Royal Bank consortium it would eliminate the risk of a possibly costly and time-consuming lawsuit.

Bank of America could take LaSalle’s retail operation while Royal Bank of Scotland is more interested in LaSalle’s commercial banking business in Illinois and Michigan, which it would combine with Citizens, its existing and retail-focused operation in the region.

ABN shareholders will vote on the LaSalle sale at an extraordinary shareholder meeting later this year. A date for the meeting has not been set.

In the meantime, both bidders will have to woo ABN shareholders, who may hold out for an increased offer from Barclays.

Royal Bank of Scotland and its partners will have to convince ABN shareholders that its bid is superior to that of Barclays even though it may bear some risks.

Royal Bank and its partners said today that “they will be able to create stronger businesses with enhanced market presence and growth prospects.”

Maria Jose Lockerbie and Gerry Rawcliffe, analysts at Fitch Ratings in London, pointed toward the “significant” execution risk of the consortium bid because a company break-up on such a large scale had never been attempted.

Barclays will need to explain to shareholders why they should opt for a lower bid and one that is all in shares. John Varley, the chief executive of Barclays, said last week that the bank was making “excellent progress” in making the necessary regulatory filings for its bid to succeed.

ABN’s management, which had said it preferred the Barclays bid because it avoided a breakup of the bank, had criticized the Royal Bank of Scotland consortium for not guaranteeing financing for the bid.

The three banks said today that Royal Bank will pay 27.2 billion euros, Fortis 24 billion euros and Santander 19.9 billion euros. Royal Bank of Scotland will issue about 15 billion euros of new shares to ABN shareholders and raise an additional 6 billion euros in capital.

Fortis will raise 15 billion euros through a rights offer, about 5 billion euros in additional capital and as much as 8 billion euros by selling assets and securities, it said.

Santander plans to raise as much as 10 billion euros through a rights offer and by selling mandatory convertible securities. The three banks said their bid was fully underwritten by Merrill Lynch, the investment bank that also advised the group on the bid, and sub-underwriters.

The consortium also laid out how it planned to break up ABN Amro. Royal Bank of Scotland will take over ABN’s North American business, including LaSalle, and all wholesale clients except in Italy and Brazil.

Fortis will take the Dutch retail businesses, private clients operations and asset management businesses.

Santander will acquire Banco Real in Brazil and Banca Antonveneta in Italy. The three banks will share control over ABN’s head office and central functions, the private equity portfolio and stakes in Capitalia, the Italian bank that is being bought buy UniCredit, Saudi Hollandi and Prime Bank.

ABN Amro said Tuesday that its board was studying the offer and was expected to respond within days.

(Published by The New York Times, May 29, 2007)