By Carolina Pulice

Former Americanas Chief Executive Miguel Gutierrez has denied in a letter sent to congressional investigators any knowledge of accounting irregularities during the two decades he helmed the Brazilian retailer.

Gutierrez said he never "participated, authorized, ordered, tolerated or became aware of any act tending to manipulate the company's accounting or to enable any type of fraud," according to a Sept. 4 letter sent to the congressional committee investigating the retailer's near-collapse which was viewed by Reuters.

Americanas quickly disputed Gutierrez's assertion, reiterating in a statement that independent advisers it had hired had found that management at the time had "fraudulently altered" documents to hide the circumstances that led to its bankruptcy filing.

Americanas, which runs of chain of brick and mortar stores and one of Brazil's largest e-commerce retailers, was thrown into crisis early this year by the disclosure of more than 20 billion reais ($4 billion) of accounting inconsistencies.

Allegations that Gutierrez and other senior management were involved in accounting fraud were first made in June.

The letter marks the first time that Gutierrez has addressed the allegations.

Several former Americanas directors have testified before the congressional committee in the last few weeks. Gutierrez has been invited to testify but he has said that health issues have impeded him from doing so.

In the letter, Gutierrez also said that reference shareholders in Americanas from investment firm 3G Capital, who together own a third of the retailer, and board members "had responsibilities relating to the financial and accounting issues of the company."

A 3G spokesperson did not immediately respond to a request for comment outside business hours.

Gutierrez's immediate successor Sergio Rial said in testimony last week before the congressional committee that he had not seen any evidence that the reference shareholders or board members had participated in the fraud.

($1 = 4.9373 reais)

(Reporting by Carolina Pulice; Editing by Edwina Gibbs)