The European Commission yesterday waded into a developing political row over a Royal Bank of Scotland consortium's break-up bid approach to Amsterdam-based ABN Amro - warning the Dutch central bank not to discriminate against any offers.

European Internal Market Commissioner Charlie McCreevy's stern warning came the day after De Nederlandsche Bank, the Dutch central bank, claimed a consortium bid would be risky. A spokesman for McCreevy yesterday highlighted the fact that the Netherlands had played a key part in the recent introduction of anti-protectionist legislation across the European Union.

Royal Bank, long-time Spanish ally Santander and Belgian-Dutch insurer Fortis made it plain in a statement last night, confirming they would meet with ABN Amro on Monday, that they expected their Dutch target's board to afford their proposals the same consideration as any from Barclays.

ABN Amro, which had a stock market worth of about 68bn (£46bn) last night, has been in exclusive talks with London-based Barclays for several weeks. This period of exclusivity is due to end today.

Royal had suffered its first setback in its break-up bid plan for ABN Amro on Wednesday, when the DNB said such a consortium offer "would constitute a strong risk-increasing and complicating factor".

However, former Irish finance minister McCreevy leapt to the Scottish bank's defence yesterday through Oliver Drewes, his spokesman.

Drewes said: "All bids should be assessed in a non-discriminatory way."

ABN Amro chief executive Rijkman Groenink played a part in the EU legislating against protectionism by being among the executives to claim some regulators were abusing their powers to protect domestic banks. ABN Amro's efforts to acquire in Italy were hampered significantly by the Bank of Italy.

Drewes yesterday noted the Dutch had backed strongly the introduction of tougher rules across the EU to crack down on political interference in banking mergers.

Making it plain McCreevy therefore expected more of the Dutch, Drewes added: "Commissioner McCreevy is disappointed if any member state goes down the protectionist route but would be even more disappointed if this is done by the Netherlands, which again stood at the origins of the current directive."

One source sympathetic to the Royal consortium said this last comment was "excellent".

In a joint statement last night, the consortium members attempted to ramp up the pressure on ABN Amro's board to give them a proper hearing and hit back at the Dutch central bank.

In a pointed response to the DNB, they said: "Fortis, Royal Bank of Scotland and Santander have written to ABN Amro confirming attendance at a meeting on Monday 23 April to clarify their intentions and interests, which they are confident are straightforward from a shareholder, regulator, and execution perspective."

The DNB had said on Wednesday: "From a prudential point of view, an offer by a consortium would constitute a strong risk-increasing and complicating factor, both in the preparation of the trans- action and in its execution and implementation "Given its role as prudential supervisor and central bank, DNB, responsible for the soundness and prudence of banking policy, will assess a concrete proposal, should one be made, with meticulous care. DNB will, among other things, examine whether the parties have succeeded in adequately addressing said risks."

The consortium members, emphasising the seriousness of their intent, added in last night's statement: "The banks welcome the opportunity to present their proposals to ABN Amro so that they can be considered by the board of ABN Amro alongside any proposals from Barclays."

There has been speculation that the consortium might be able to pay up to 40 a share for ABN Amro, which saw its shares dip 1% to 35.76 yesterday.

The indications have been that ABN Amro has been trying to wring a bid of more than 35 a share from Barclays, a price viewed as a significant stretch for the UK bank.

ABN Amro and Barclays have said the headquarters of an enlarged bank formed by any deal they might do would be in the Netherlands.

This option is viewed by observers as much more palatable for the DNB than a break-up of a Dutch icon.

Analysts have speculated the Royal consortium could pay more for ABN Amro than Barclays because the three members would each take the parts of the Dutch bank which fitted best with their existing strengths and could thus extract greater value.

Royal is interested in the Dutch institution's corporate banking activities, and its operations in the US, including LaSalle, and in Asia. Santander wants ABN Amro's operations in South America, including Brazil, and in Italy.

Fortis has its eye on ABN Amro's lowland European retail banking business, its asset management activities, and its upmarket private client banking division.

A three-way split of ABN Amro would be Royal's second-biggest acquisition yet, exceeded only by its £21bn purchase of National Westminster in 2000.

There was talk yesterday that Spanish bank BBVA, Bank of America, and BNP Paribas of France had indicated to Barclays they might be interested if the UK bank wanted to sell parts of ABN Amro after a deal.

Such disposals might boost the price Barclays could pay for ABN Amro. However, sources at BBVA said later that it was focused at the moment on integrating the banks it had bought in the US, and was also concentrating on a new plan to streamline working practices.