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The bank said it has made most of the 107 regulatory filings across 52 countries it needed to proceed.

The announcement comes amid a small, but notable, chorus of concerned voices from investors who don't see the logic of a Barclays ABN tie-up.

Two US hedge funds have so far expressed fears over a possible merger.

Atticus Capital said it was concerned Barclays could get sucked into "an auction at inflated prices" after buying a 1% stake in the group.

It said it would vote against the deal and urge other investors to do the same.

The hedge fund's concerns were echoed by another US institutional investor, Seacliff Capital, which has cut its relatively small stake in Barclays by half since news of the bid first broke, the Financial Times reports.

Privately, there are also concerns among the larger fund management groups that Barclays will raise its bid to outdo the RBS-led team, according to analysts.

But John Varley, Barclays chief executive, reiterated that the ABN offer provided "significant and sustained value" for shareholders.

LaSalle tug-of-war

A key element in the Barclays bid was the plan by ABN Amro to dispose of its US subsidiary LaSalle to an American bank.

Barclays noted that Bank of America has submitted its application to the US Federal Reserve to buy ABN's LaSalle stake.

The sale was blocked by a Dutch court in May.

The Amsterdam commercial court ruled that ABN's management could not go ahead with the sale of LaSalle to Bank of America without first putting the decision to a vote by shareholders.

Some shareholders took the view that the sale was a deliberate spoiler to prevent a higher offer being made by an investment consortium led by Royal Bank of Scotland.

The group, which includes Belgium's Fortis and Banco Santander of Spain, has outlined a proposed offer for ABN Amro which values the Dutch bank at 71.1bn euros.