The U.S. judge presiding over the fraud trial of former press baron Conrad Black on Monday denied the request of a co-defendant for a mistrial.

John Boultbee, a former chief financial officer at Hollinger International, had asked for a mistrial and to be tried separately from Black.

On Monday morning in a Chicago courtroom, Judge Amy St. Eve turned down Boultbee's requests.

Black, 62, Boultbee and two other former Hollinger International executives face charges of fraud, accused of swindling the company out of $80 million US. All four have pleaded not guilty.

Boultbee's lawyer, Gus Newman, had argued in favour of the mistrial and separate trials by saying that questions from the lawyer of another co-defendant, Peter Atkinson, could produce testimony prejudicial to his client.

Atkinson's lawyer, Michael Schacter, had been cross-examining Fred Creasey, the former comptroller at Hollinger International.

The lawyer was asking about non-compete payments made to Black, Boultbee, Atkinson and a fourth accused, Mark Kipnis.

Despite denying the request for the mistrial, the judge said she would limit testimony to comments made by Atkinson to the audit committee of Hollinger International.

Schachter was attempting to show that Atkinson had no plans to hide information about the non-compete payments.

The payments were made to Black and other executives by companies and individuals who purchased hundreds of Hollinger newspapers in North America.

The money was given in exchange for a promise that Hollinger wouldn't compete with them.

Non-competition payments are not unusual, but prosecutors  say the payments should have gone to Hollinger shareholders, not to Black and his fellow executives.

The trial started in mid-March.

With files from Canadian Press