In its first official statement since the onset of the sub-prime market crisis, Northern Rock yesterday said it had minimal exposure to US sub-prime mortgages and that it had sold nearly £500m of commercial property loans.

Northern Rock said it had just £275m invested in US mortgage-backed securities, accounting for just 0.25% of its total assets.

Northern Rock also announced that it had sold £465m of commercial property loans to Lehman Commercial Mortgage Conduit, a division of Lehman Brothers. The sale follows a disposal of £838m of loans to the same buyer in June.