Barclays unveiled two new U.S. regulatory probes on Wednesday as the bank, already rocked by an interest rate rigging scandal, said profits fell by a fifth due to charges for the mis-selling of insurance.

Barclays said the U.S. Department of Justice (DOJ) and U.S. Securities and Exchange Commission were investigating whether its relationships with third parties who help it win or retain business are compliant with the U.S. Foreign Corrupt Practices Act. It is also being investigated for past power trading in the western United States.

The bank reported an adjusted pretax profit in the three months to the end of September of 1.73 billion pounds ($2.8 billion), in line with analysts' forecasts and up from 1.34 billion a year ago, thanks to strong profits from investment banking. But including a 700 million pound charge for mis-selling payment protection insurance would have left profits down 23 percent at 1.03 billion.

(Reporting by Steve Slater and Matt Scuffham)