One of Royal Bank of Scotland's partners circling ABN Amro, the Belgian-Dutch bank Fortis, has kick-started its mammoth €15 billion fundraising to back the deal by selling €2 billion of debt securities linked to a forthcoming rights issue.

Shares in Fortis, listed on the Amsterdam bourse, fell more than 1 per cent in early trading

If the rights issue goes ahead, the notes convert into shares in Fortis. If it doesn't, the bank buys them back at face value next month, August 4.

The complex financial move underscores the difficulty faced by Fortis, which has to foot just over a third of the consortium's €71 billion bill for its ABN bid.

A spokeswomen for Fortis said the "conditional capital exchangeable notes" being issued today were a standard instrument in the capital markets. However, she acknowledged that Fortis would have to use multiple financing techniques in order to raise the full €15 billion.

"You always have to find the right balance between what you have to offer to investors and what is right for Fortis," she said.

Fortis shareholders still have to grant approval for a rights issue the bank is preparing.

Today's financing, being run by Fortis adviser Merrill Lynch, involves Fortis selling securities worth up to €2 billion. These will pay interest of up to 0.2 per cent above Euribor, or the rate European banks charge to lend to each other.

Only professional investors can buy the notes, available in minimum ticket sizes of €250,000 each. The price of the securities should be struck today and Fortis hopes to have the funding wrapped up by August 2.

Fortis said that the deal would allow it to collect cash ahead of the planned ABN Amro offer without having to issue new shares unless the deal actually gets the go-ahead.

"This transaction enables Fortis to proactively address its planned capital needs for the proposed offer for ABN Amro through a contingent instrument that will not result in a capital issuance unless required," it said.

The RBS consortium, also joined by Santander of Spain, is on tenterhooks ahead of a Dutch Supreme Court ruling on Friday that is expected to ring-fence ABN's prized American division LaSalle from the bid.

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