Embattled newspaper magnate Conrad Black resigned as chief executive of Hollinger International on Wednesday, two days ahead of the scheduled date.

He told the company's board of directors that he made the move "on advice of counsel," Hollinger said in a release.

Black's early departure meant he was unable to sign a certification for the company's financial results for the quarter that ended Sept. 30. The deadline for that filing was Wednesday.

Black's resignation followed news that U.S. and Canadian securities regulators are investigating the company, probably looking into $32.5 million US of non-competition payments made to Black and other Hollinger officials.

The payments, including $7.2 million to Black, are controversial because they were not properly disclosed, or disclosed incorrectly, or not properly approved.

Hollinger said Wednesday that the U.S. Securities and Exchange Commission had issued subpoenas to the company, its audit committee and its auditors, KPMG, requesting documents.

The company and the audit committee members of the board of directors "intend to co-operate with the SEC's request and that of all other governmental authorities."

Regulators at the Ontario Securities Commission said Wednesday they are looking into events at Hollinger.

Eric Pelletier, a spokesman for the OSC, told CBC Business News that the commission is "making inquiries" into Hollinger matters, has been in contact with the SEC, and will continue co-ordinating with U.S. regulators.

He would not elaborate.

An independent committee of Hollinger's board found the "unauthorized" payments made to the executives and to parent company Hollinger Inc. following the sale several U.S. newspapers. Black has agreed to repay his share.

Black has repeatedly denied any impropriety.