The battle for ABN Amro, the Dutch bank, shifted Barclays’ way yesterday after banking supervisors in the Netherlands fired a shot across the bows of the rival bidding consortium led by Royal Bank of Scotland.

De Nederlandsche Bank (DNB), which supervises banks in the Netherlands, said that a break-up bid from the RBS consortium “would constitute a risk-increasing and complicating factor”.

In a strongly worded statement, it told RBS and its consortium members, Banco Santander, of Spain, and Fortis, of Belgium, that it would scrutinise any proposal meticulously to ensure that all risks had been properly addressed.

In a response that appeared to pitch regulator against regulator along national lines, the Governor of the Bank of Spain said that he could see no problem with the proposal. Miguel Ángel Fernández Ordóñez said: “I don’t for the moment recognise [the risks referred to by DNB].”

However, share traders took the DNB statement as lengthening the odds on a successful RSB consortium bid and marked ABN Amro’s shares 0.7 per cent lower to €36.13.

ABN Amro, although still in exclusive talks with Barclays until tomorrow, has agreed to talk to the RBS grouping next week, although it is still reluctant to open its books to banks that it regards as being arch competitors.

The Children’s Investment Fund (TCI), the activist hedge fund that chivvied ABN into merger talks last month, kept up the pressure yesterday, saying that the decision to delay talks with RBS was “disingenuous and disadvantageous for shareholders”.

The delay meant that the talks will take place only after the 5pm deadline by which ABN shareholders have to register to vote at the annual meeting on April 26.

However, ABN won support from other shareholders yesterday, with Delta Lloyd Asset Management, which owns more than 1 per cent of it, backing the Barclays talks. Alex Otto, a Delta spokesman, said: “In the long run, we have the feeling that ABN Amro would be most valuable through Barclays.” TCI was seeking short-term results, Mr Otto added.

The DNB intervention adds supervisory concerns to competition worries that could also scupper the RBS approach. Fortis, which wants to take over ABN’s domestic operations, would have a very high market share in small business banking and credit cards. There could also be resistance from American competition regulators because of plans for RBS to take control of ABN’s LaSalle bank. Although the Chicago-based LaSalle mostly complements RBS’s Citizens Bank, there is much overlap in Detroit, where divestments could be required.

Official view

‘From a prudential point of view, an offer by [the RBS consortium] would constitute a strong risk-increasing and complicating factor, both in the preparation of the transaction and in its execution and implementation . . . DNB will, among other things, examine whether the parties have succeeded in adequately addressing said risks.’ DNB

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