Bank of America will come under increasing pressure this week to rescind its offer to put a top Countrywide executive in charge of the companies' combined mortgage business after reports that Countrywide is the subject of a criminal investigation by US authorities.

David Sambol, president and chief operating officer of the embattled US mortgage lender, is due to take over the role following the completion of BofA's $4bn take-over of Countrywide.