Wells Fargo & Co. said employees created two-thirds more bogus accounts than initially thought, a sign the bank is still struggling to move past a scandal that sparked record fines and congressional investigations.

An outside review found an additional 1.4 million potentially unauthorized deposit and credit-card accounts opened when the bank was encouraging employees to sell multiple products to retail customers, bringing the total to about 3.5 million, according to a statement Thursday from the San Francisco-based firm. The revised estimate covers January 2009 to September 2016, almost twice as long as the period examined in the initial review.

The disclosure of even more fraudulent accounts threatens to catapult Wells Fargo back into the political crosshairs just as Congress returns Sept. 5 from its summer recess. The scandal came to light almost a year ago after regulators slapped Wells Fargo with fines of $185 million over its sales practices, prompting congressional hearings and resulting in the bank naming new leaders, clawing back executives' pay and beginning an overhaul of its retail division.