TORONTO - Conrad Black's lawyers are asking an appeal court to throw out his guilty convictions Friday, saying prosecutors failed to prove he had "guilty knowledge" of any fraud and describing his obstruction of justice conviction as "preposterous."

Lawyers for Black, who began serving his 6 1/2-year jail term at a Florida prison last week, told the U.S. Seventh Circuit Court of Appeals that the 63-year-old should get his fraud and obstruction of justice convictions overturned or at least get a new trial.

"Black didn't have any guilty knowledge; there's no evidence of the mental evidence of the offence, which is knowing that you're stealing money that you're not allowed to get," his lead appeal lawyer, Andrew Frey, said in an interview Friday.

The 100-page court filing, which was crafted with Black's help from prison over the last week, attacks several issues in the case including government claims that Black and other executives deprived shareholders of Hollinger International of honest services and certain instructions given to the jury.

Frey said he spoke twice with Black, over the telephone, since he reported to Coleman prison in central Florida.

"He's trained as a lawyer himself, he's a smart guy, and we wanted to get his thoughts," Frey said.

"We didn't really speak too much about how he's doing, but he would say he was doing fine no matter what, because that's his personality.

"I'm sure it must be stressful, but he's a strong person and he'll do what he has to do."

Black's wife, Barbara Amiel Black, and his daughter, Alana Black, "are visiting him with some frequency," Frey added, saying he thought the transition was very hard on them.

"It's always tough on the family."

Black, once the head of the world's third-largest media empire, was convicted in July of three counts of fraud and one count of obstruction of justice in connection with millions of dollars prosecutors said were illegally pocketed from Hollinger. A Chicago jury acquitted him on nine other charges.

"This was an extraordinary case: The jury acquitted defendants on all of the counts reflecting the government's principal theory ... (and) convicted on a rump set of counts for which the evidence was insufficient and the legal theory invalid," the filing said.

Black and his lawyers have consistently dismissed the government's case, saying it was based solely on the dubious evidence of David Radler, Black's former business partner.

Radler is serving a 29-months sentence in Pennsylvania after cutting a deal with prosecutors to testify against Black.

Frey also dismissed Black's obstruction conviction Friday, saying that "the idea that he would of thought that there was some smoking gun that he needed to secret is preposterous."

Black was convicted of obstruction of justice after jurors watched a video of him hauling boxes of documents out of his Toronto office and loading them into his car.

Prosecutors said he was trying to hide evidence of financial wrongdoing from U.S. Securities and Exchange Commission investigators. But the appeals brief said Black had been "removing from his longtime office personal papers and effects, on the eve of his eviction from the space by new management, and in full view of others, including his assistant and security cameras."

"There was no evidence whatsoever of any intent to obstruct justice."

If the bid for an acquittal fails, defence lawyers are asking for a new trial, since, they say, Judge Amy St. Eve "permitted the prosecution to take two crucial evidentiary shortcuts during the trial."

One was a so-called "ostrich" instruction in which jurors were told that ignorance of wrongdoing was not an excuse if Black had deliberately looked the other way. The other alleged shortcut was allowing the government to introduce "uncharged, inaccurate SEC disclosures filed long after the fact."

"I believe what happened (at the trial) is that the jury saw all these charges, all these claims, all of the smoke screens that the prosecutors were throwing up - they didn't buy the basic prosecution theory, but they weren't prepared to acquit on everything. And so they ended up basically making a deal and splitting the baby, and convicted on a few relatively more minor things," Frey said.

"If you look at those minor things in isolation, they don't stand up very well, and I believe that a trial focused on those counts...is going to produce an acquittal. We feel pretty good that we'd win a new trial if we got one."

Jacob Frenkel, a former U.S. prosecutor who has followed the case, said the issues of deprivation of honest services and jury instructions will be serious ones for the appeal court to consider, but the obstruction will be hard to overcome.

"The appellate court (has already) said that even if they were to prevail on the fraud charges, the obstruction alone would result in a sentence," Frenkel said.

If these arguments are all they have to refute the obstruction, "Black ought to get comfortable with his new surroundings," he said.

Black, now known as inmate 18330-424, has a projected release date Oct. 30, 2013.

Under federal U.S. regulations, Black will have to serve at least 85 per cent of his sentence, with the extra 15 per cent given as credit for good behaviour. That means he's unlikely to get out of prison for five and a half years.