Britain's Serious Fraud Office formally begins criminal investigation of Barclays' rate-fixing

LONDON - Britain's Serious Fraud Office says it has formally opened a criminal investigation of Barclays' manipulation of a key market interest rate.

The agency said Friday that it was uncertain whether the investigation would result in charges.

Barclays was fined $435 million last week by U.S. and British agencies for making false reports of its borrowing costs between 2005 and 2009.

This week, Bob Diamond resigned as chief executive of the bank and Chairman Marcus Agius announced his intention to leave as soon a replacement has been appointed.