Hollinger, the troubled media firm which owns the Daily Telegraph, is facing an inquiry by US regulators.
The Telegraph is Hollinger's flagship publication
The Securities and Exchange Commission has served a subpoena - a legally binding request for information - on the company.
Hollinger chief executive Conrad Black resigned on Monday after a row over unauthorised payments to executives.
Lord Black has said he will now step down immediately, two days earlier than previously planned.
The company has pledged full cooperation with the SEC, which is seeeking documents from Hollinger's internal audit committee relating to the controversial payments.
Hollinger auditors KPMG have also received subpoenas, Reuters reports.
The company, which also owns the Sunday Telegraph, the Chicago Sun-Times, and the Jerusalem post, has said it may put itself up for sale.
The crisis was precipitated by an internal investigation which revealed that Lord Black and other Hollinger executives had pocketed $32m without the approval of the firm's audit committee.
The money came from 'non-competition' fees paid by buyers of Hollinger titles in return for an undertaking that the firm would not launch new rival products.
The revelation angered Hollinger shareholders, who argued that the money should have been ploughed back into the company.
Lord Black has denied all wrongdoing.
He and the other executives involved have agreed to repay the money in full, with interest, by June next year.
Hollinger shares closed 2.9% lower at $15.30 on the New York Stock Exchange.