Many bankers believe securities backed by US mortgages will only stabilise once US house prices stop falling.

The bank said its US business had set aside $3.2bn in bad debt provisions in the first quarter.

This is double the amount it provided in the first three months of last year, but lower than the $4.6bn set aside in the fourth quarter of 2007.

HSBC also said it had benefited from a $2.7bn one-off gain in the quarter, reflecting the reduced value of the bank’s own debt,

Nevertheless, Douglas Flint, finance director, said the recent revival in the markets had not extended to more complex mortgage-backed securities.