U.S. President Donald Trump has granted a full pardon to former media mogul Conrad Black, with the White House calling him "entirely deserving" of the gesture.

Black, who and recently published a glowing biography of the president, served nearly 42 months in a Florida prison after he was convicted for fraud and obstruction of justice in 2007. He was also fined US$125,000.

Black said Trump called him last week to personally deliver the news.

In an interview with 麻豆影视鈥� Omar Sachedina Wednesday night, Black said he initially thought the phone call was a prank, but quickly realized that it really was the president of the United States on the other line.

Black said 鈥渋t was very, very gratifying鈥� to receive the pardon.

鈥淚t has not been a day at the beach to go through all this,鈥� he said. 鈥淚 was innocent 鈥� There was no substance to any of the charges. There never was. The whole thing gradually disintegrated.鈥�

Black also issued an exhaustive 1,698-word statement expressing his gratitude to Trump and others who lobbied on his behalf over the years.

鈥淗e could not have been more gracious and quickly got to his point, that he was granting me a full pardon, that would 鈥楨xpunge the bad wrap [sic] you got,鈥欌�� Black wrote.

鈥淭he American criminal justice system is frequently and largely evil; I was convicted for attempted obstruction of injustice. It was never anything but a smear job.鈥�

In a statement, White House press secretary Sarah Sanders described Black as 鈥渁n entrepreneur and scholar鈥� who has a 鈥渄istinguished reputation for helping others鈥� and worked as a tutor in prison.

鈥淚n light of these facts, Mr. Black is entirely deserving of this Grant of Executive Clemency,鈥� the statement read.

Black has long been a vocal supporter of Trump. Last year, Black published a flattering biography of Trump, "Donald J. Trump: A President Like No Other,鈥� in which he highlighted what he considers the president鈥檚 biggest successes.

After the book was published, political observers speculated that Black may have been angling for a presidential pardon. He denied doing so Wednesday in the interview with 麻豆影视, but offered the hypothetical scenario that if he was a Trump critic, the president may have acted differently.

鈥淚 wouldn鈥檛 count on him responding as he has. But that is entirely hypothetical,鈥� he said. 鈥淭here is no doubt in my mind that while he was happy to do it for personal reasons, he is satisfied, and the White House counsel confirmed him in this, that I never should have been charged and certainly never should have been convicted.鈥�

Black doesn鈥檛 think his book had anything to do with Trump鈥檚 decision to issue the pardon.

鈥淚 have no reason to believe he鈥檚 read it and he鈥檚 never mentioned it to me,鈥� Black said Wednesday. 鈥淚 take him at his word that his motive was what he said it was.鈥�

Black said that he and Trump are 鈥渘ot close now,鈥� but were always friendly in the past, adding that they were business associates on a project in Chicago and were neighbours in New York and Palm Beach.

鈥淚 have not heard from him since he was president-elect, up until last week, when he called,鈥� he told Sachedina.

Black said he does not have a direct line to the U.S. president.

鈥淚 would never dream of bothering a person in a position like that. I would never have occasion to presume to phone the President of the United States,鈥� he said. 鈥淗e鈥檚 got other things to do than take calls from me.鈥�

In 2015, when Trump was running to be the Republican nominee for president, Black wrote a piece for The National Review calling Trump 鈥渢he good guy鈥� in the race.

The article caught the attention of then-candidate Trump.

"What an honor to read your piece," . "As one of the truly great intellects & my friend, I won't forget!!"

Black responded in kind.

"Many thanks, Donald and all good wishes in helping to clean up the American government. Honored to be your friend," .

His feelings on the Trump presidency haven鈥檛 changed. While he conceded that Trump has 鈥渟tylistic foibles,鈥� Black isn鈥檛 bothered: 鈥淗e is who he is and I think he鈥檚 done an excellent job.鈥�

Black previously headed Hollinger international, a global newspaper publisher that published The National Post, The Daily Telegraph and The Jerusalem Post. He famously renounced his citizenship to Canada in 2001 to become the Lord Black of Crossharbour, his official title as a British lord.

In 2007, Black was convicted of three counts of fraud and one of obstruction of justice in a Chicago court and sentenced to six and a half years in jail. Two of the criminal fraud charges were dropped on appeal. But a conviction for felony fraud and obstruction of justice were upheld in 2010.

He has been banned by the Ontario Securities Commission from acting as a corporate director or officer of a public company in Ontario. He was also removed from the Order of Canada.

With files from The Canadian Press