The war of words between ABN Amro and a bidding consortium led by Royal Bank of Scotland escalated today as the Dutch market regulator forced the publication of previously confidential exchanges between the two groups.

As the tit-for-tat letter and e-mail exchanges centred on the RBS team's financing of any ABN deal, the Dutch No 2 bank reiterated that its rejection of a €71 billion (£48.4 million) proposal this month was based on concerns about a lack of clarity over how the Edinburgh bank's consortium planned to pay for its proposed acquisition.

ABN stated that it had received no contact from RBS - or its partners at Fortis Bank and Banco Santander - since it rejected their initial approach on May 6.

The RBS consortium, which is trying to break up an agreed deal deal worth €63 billion between ABN and Barclays, insisted that all of its financing was firmly in place and its takeover plan would not be subject to any financing conditions or on any asset disposals.

Contained within a raft of published documents from both sides, including two 70-page draft takeover agreements, were several question and answer exchanges in which ABN and its lawyers sought further detail about the RBS camp's proposal and its financing plans.

As well as three pages of questions about funding for the consortium, dubbed RFS Holdings, ABN also released an e-mail purported to be sent by Matthew Greenburgh, the top Merrill Lynch banker working for the RBS team.

In the e-mail, Mr Greenburgh appears to shun the Dutch bank's requests for further financing. "As discussed earlier today, we believe we have provided sufficient information for you to be able to determine that our acquisition proposal is superior, subject only to confirmatory due dilligence," the e-mail states, underscoring not only the emphasis on funding, but the increasingly tense nature of exchanges.

RBS has come under increasing pressure from ABN to clarify the funding behind its initial bid for LaSalle, ABN's American arm, which was conditional on the success of a bid for the wider group.

In one of the letters published today and dated May 3, the RBS team claimed some of the banks that were advising ABN had approached it with offers to provide help funding the RBS consortium's bid.

Documents published by the bid trio repeated that Merrill Lynch had agreed to underwrite all equity and debt issuance made by any consortium member bank, each of which had also received other underwriting offers. Debt and equity will be issued to fund a part cash, part share acquisition, the banks said.

The RBS team is planning to offer €38.40 a share for ABN, comprising €27 in cash and €11.40 in new RBS shares. This compares with Barclays €36.25 offer, consisting entirely of Barclays stock.

RBS said it remained convinced its proposal was "superior" to Barclays and that it could better-manage the bank and extract more efficiencies following a takeover.

In the event of a successful deal, RBS would control businesses including LaSalle in North America, global clients and wholesale businesses worldwide outside Brazil, and Asia and Europe apart from Antonveneta in Italy.

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