Number of NHS trusts in financial difficulty has more than doubled in a year, an Audit Commission report warns.

Hospitals on the outskirts of London and across the south east are struggling to balance their books, according to the report, while those in the centre of the capital, the Midlands and northern England are tending to fare much better.

Across England, the Audit Commission found 31 ended the 2011-12 financial year with a deficit. That compares with just 13 at the end of the previous year.