April 27 (Bloomberg) -- A group led by Royal Bank of Scotland Group Plc plans to make an unsolicited offer for ABN Amro Holding NV, escalating the fight with Barclays Plc for control of the biggest Dutch bank.

Royal Bank, Santander Central Hispano SA and Fortis today said in a statement they intend to make an offer after indicating two days ago they would pay 72.2 billion euros ($98.2 billion) for ABN Amro. That would trump an all-share accord with Barclays, valued at about 64.7 billion euros at the close of trading.

``They're ratcheting up the pressure on the ABN Amro board,'' said Robert Talbut, who helps manage about 31 billion pounds ($62 billion), including ABN Amro, Royal Bank and Barclays stock, as chief investment officer of Royal London Asset Management. ``It shows the group is serious about putting forward its proposals and they want cooperation from the ABN board.''

The Royal Bank-led group said today's statement was prompted by ABN Amro's decision to sell Chicago-based LaSalle Bank to Bank of America Corp. for $21 billion. The banks have said their bid depends on ABN Amro canceling the sale.

ABN Amro said in a statement after the close of trading today that it would allow the three banks to carry out due diligence without a so-called standstill agreement. The requirement would have prevented the trio from making an offer for 12 months without the Dutch bank's consent. The Royal Bank group had requested the provision be dropped.

ABN Amro shares rose 1.2 percent today in Amsterdam to 36.75 euros, valuing it at 70.2 billion euros. The stock has surged 35 percent since it announced talks on March 19. Barclays shares rose 1 percent to 725.5 pence in London and those of Edinburgh- based Royal Bank slipped 1.5 percent to 1,940 pence.

`Alternative Bids'

ABN Amro, based in Amsterdam, said yesterday it's ``soliciting alternative bids'' for LaSalle. Chief Executive Officer Rijkman Groenink and ABN Amro's board have favored Barclays because the third-biggest U.K. bank plans to keep the company mostly intact. The Royal Bank-led group intends to break up the 183-year-old Dutch bank if its bid succeeds.

The banks ``notified the supervisory and managing boards of ABN Amro yesterday evening of their intention to make a public offer for 100 percent of the issued and outstanding share capital of ABN Amro on a fully diluted basis,'' the group said today. ``Their proposals offer materially higher value for ABN Amro's shareholders and benefits to customers and employees compared with the recommended offer from Barclays.''

`Moving Quickly'

ABN Amro shareholders voted at the company's annual meeting yesterday to endorse a call for a breakup or sale.

The meeting in The Hague was disrupted by protests from the VEB Dutch investor group that the LaSalle sale may deter Royal Bank from outbidding Barclays. The Enterprise Chamber of the Amsterdam district court said it will hear the VEB's request to investigate and suspend the sale tomorrow.

``The Royal Bank group clearly now want to move quickly given the agreement to sell LaSalle,'' said James Hutson, a London-based analyst at Keefe, Bruyette & Woods Ltd., who has a ``market perform'' rating on Royal Bank stock.

Under ABN Amro's agreement to sell LaSalle to Charlotte, North Carolina-based Bank of America, a counter-bidder has 14 days to submit a higher offer in cash. Bank of America then has five days to match the bid. If it doesn't, it's entitled to a $200 million termination fee.

ABN Amro spokesman Neil Moorhouse declined to comment. The takeover would be the world's biggest bank acquisition.

The Dutch bank yesterday said first-quarter net income was little changed at 1.04 billion euros after taking a 365 million- euro provision for the likely settlement of a U.S. Department of Justice criminal probe into transfers from sanctioned countries.

`Agreement Preferred'

Royal Bank CEO Fred Goodwin has a history of winning fights, having beaten Edinburgh-based rival Bank of Scotland in 2000 for National Westminster Bank Plc. NatWest shareholders accepted Royal Bank's hostile 23.6 billion-pound offer after a five-month battle.

``Our preference is to find an agreed way through this,'' Goodwin said April 25 when proposing the group's approach to ABN Amro. ``We would expect ABN to work to help us.''

ABN Amro and Barclays disclosed their negotiations on March 19. Royal Bank, the No. 2 U.K. bank after HSBC Holdings Plc, and its partners said April 13 they asked for ``exploratory talks.''

ABN Amro agreed on April 23 to Barclays's offer of 3.225 new shares for each share of ABN Amro. Shareholders may also qualify for Barclays's final dividend for 2007.

`Wriggle Room'

``Management has got to open this up and make it a fair contest,'' said Nigel Bolton, head of European stocks at Scottish Widows Investment Partnership in Edinburgh. He helps manage 102 billion pounds, including ABN Amro shares. ``We expect to see a higher offer from the other side, or this will be done deal.''

Barclays still has ``wriggle room'' for its offer, Keefe Bruyette & Woods analysts wrote in a report today, saying it has 1.5 billion pounds in surplus cash.

``The merger is clearly articulated and deliverable,'' Barclays CEO John Varley said today in comments passed on by spokesman Stephen Whitehead. Barclays's offer ``provides ABN shareholders with immediate value through a substantial premium and the ability to share in the significantly enhanced growth of the merged company,'' he said.

``I'm not surprised by the recent machinations and game- playing,'' Varley said. Yesterday he said the bank is not contemplating raising its bid for ABN.

`Finely Balanced'

Santander, Spain-based Santander, the country's biggest bank, said today first-quarter profit rose 21 percent to 1.80 billion euros on revenue growth in Spain and lower costs at its U.K. mortgage unit. Fortis, based in Brussels and the Dutch city of Utrecht, is Belgium's biggest financial-services company.

The group has seven days from April 25 under Dutch law to confirm its indicated bid and cannot disclose a proposed price during that period.

``It seems that RBS and its partners have no intention of withdrawing from the contest for the time being,'' London-based Bear Stearns Cos. analyst Robert Sage wrote in a note to investors. ``We still view the outcome of the situation as finely balanced.''

To contact the reporter on this story: Ben Livesey in London blivesey@bloomberg.net.

Last Updated: April 27, 2007 14:18 EDT