Britain's building societies could be forced to conduct individual investigations into their mortgage books to prove they do not have financial 'black holes' in the wake of the alleged £41m fraud that rocked Chelsea Building Society last week.

The Financial Services Authority is considering asking each building society to conduct a health check, particularly of buy-to-let businesses, according to a well- placed source.

The Serious Fraud Office and the police are already investigating buy-to-let rackets all over the country.

Sunday Telegraph