Refco, the bankrupt futures broker, held offshore accounts with up to $525m (€435m) in fake bonds, suggesting the firm's woes may be more extensive than previously reported.

A report by Bloomberg, citing four people with direct knowledge of evidence gathered by US prosecutors investigating the firm's collapse, said Refco held the securities for Bawag, Austria's fourth-largest bank, and Liquid Opportunity, an offshore hedge fund, under identification numbers that do not correspond to registered bonds.