CORRECTED - UPDATE 8-Fortis seen nationalisation-bound, BNP exits

(Corrects amount source said BNP offered in third paragraph) (Recasts with nationalisation looming, BNP Paribas pulls out)

By Reed Stevenson and Philip Blenkinsop

AMSTERDAM/BRUSSELS, Sept 28 (Reuters) - Belgian-Dutch financial group Fortis (FOR.BR) faced a shotgun nationalisation on Sunday after European Central Bank President Jean-Claude Trichet held emergency talks with Dutch and Belgian ministers on rescuing one of Europe's top 20 banks.

Sources close to the talks said the Belgian government appeared to have chosen a state buyout after investor confidence collapsed in the first spread of U.S.-style financial contagion to the euro zone, and talks with private bidders failed.

The most likely private bidder, France's BNP Paribas (BNPP.PA), pulled out after offering just 1.60 euros per share, compared to Friday's closing price of 5.20, and demanding state guarantees against possible future losses, the sources said.

Trichet, who as ECB head is responsible for safeguarding financial stability in the euro zone, joined Belgian Prime Minister Yves Leterme in Brussels in a frantic drive to secure the future of the cross-border bank and insurance group.

The presence of the ECB chief -- unprecedented in a commercial bank rescue -- underlined the seriousness of concern for the integrity of the euro zone's financial system.

Fortis' size, with 85,000 staff worldwide, and its cross-border structure made it too big to be allowed to fail. Its nationalisation would dwarf Britain's state takeover of fallen mortgage lender Northern Rock last year.

Fortis' precursors traded with Catherine the Great and financed the U.S. purchase of Louisiana from Napoleon. Its main constituent bank, Societe Generale, was the main financier of the industrialisation of Belgium and the Netherlands.