Donald Trump has said he is considering pardoning the deceased boxing great Muhammad Ali.

Ali was convicted in 1967 of refusing to report for military duty after being drafted into the Vietnam War. He declared himself a conscientious objector, citing religious reasons, but was sentenced to five years in prison and stripped of his heavyweight boxing crown.

Mr Trump said on his way to the G7 summit in Canada that his administration was "currently preparing recommendations" over Ali's case.

Mr Trump said he had a list of 3,000 names he is considering for pardon, many of whom have been "treated unfairly".

“[Ali] was, look, he was not very popular then, certainly his memory is popular now,” Mr Trump said of the late boxer.

The comments confused some, who pointed out that the US Supreme Court overturned Ali's conviction in 1971 – just four years after he was sentenced. President Jimmy Carter also granted a blanket pardon to all Vietnam War draft evaders in 1977.

Muhammad Ali: A life in pictures Show all 20 1 /20 Muhammad Ali: A life in pictures Muhammad Ali: A life in pictures Despite taking his first booking lessons with a local policeman, Clay was simultaneously coached by the more experienced Fred Stoner. Under him, the young boxer won six Kentucky Golden Glove titles, two national Golden Glove titles, and an Amateur Athletic Union National Title. His amateur success culminated when Cassius won the Light Heavyweight gold medal in the 1960 Summer Olympics in Rome. After that, Clay decided to start off his professional career. Getty Images Muhammad Ali: A life in pictures Clay won his first professional fight against Tunney Hunsaker in a six-round decision on October 29, 1960. After that, he went on to establish a record of 19-0 fights, with a total of 15 knockouts. Thanks to his high stature (1.91m), he developed a highly unorthodox style for a heavyweight boxer, relying on foot speed and carrying his hands low rather than on heavy punches. Getty Images Muhammad Ali: A life in pictures By 1963, Clay had not only built a reputation for his boxing technique, but also for correctly predicting the round in which he would "finish" the opponent. Here, he predicts (correctly) the round in which he will knock-out British boxer Henry Cooper. Other boxers Clay defeated prior to his first title fight included Doug Jones, Lamar Clark and Jim Robinson. Getty Images Muhammad Ali: A life in pictures In his first title fight, Cassius Clay opted for world heavyweight champion Sonny Liston. Though few observers thought the 22-year old could defeat an ex-con with ties to organized crime, Clay proved them wrong: in the legendary sixth round of the fight, he landed spectacular combinations of punches, seemingly at will. When Liston told his cornermen he couldn't continue to the seventh round, Clay sprang to the center of the ring, and repeatedly yelled "I’m the greatest!" and "I shook up the world". Cassius Clay had made history for the first time. Getty Images Muhammad Ali: A life in pictures The day after the fight, Cassius Clay announced that he was changing his name to Muhammad Ali for religious reasons. Although he had already been member of Nation of Islam prior to the fight, he was advised not to declare this publicly, in order not to jeopardize his chances. At that time, the Nation of Islam was often viewed with outright suspicion by mainstream America, and Ali did little to counter these impressions: the boxer once stated, for example, that "Integration is wrong. We don't want to live with the white man; that's all." However, after the death of Nation of Islam leader Elijah Muhammad in 1975, Ali converted to mainstream Sunni Islam. Later in his life, he came to embrace spiritual practices of Sufism. Getty Images Muhammad Ali: A life in pictures Muhammad Ali also aroused controversy through his outright opposition to the Vietnam War. When notified of his army classification as 1A in early 1966, the boxer declared that he would refuse to serve, as he considered himself a conscientious objector. He also famously declared about the war: "I ain't got no quarrel with them Viet Cong ... They never called me nigger." When refusing to step forward at his scheduled induction, Ali was arrested and found guilty after a 21-minute trial in June 1967, as a result of which his boxing license was suspended. Refusing to accept the verdict, Ali took the case to the U.S. Supreme Court. In June 1971, with public opinion already against the war, the highest court of the United States reversed his conviction by unanimous decision. Getty Images Muhammad Ali: A life in pictures In 1971, with the case still on appeal, Muhammad Ali was allowed to fight again - in what would become the Fight of the Century against Joe Frazier. It was a heavily promoted fight, with massive popular interest: Frank Sinatra, for example, took pictures for Life magazine. For Ali, it became one of his most crushing defeats. Despite dominating the first third of the fight, he later struggled to keep the pace and, indeed, was put on his back for only the third time in his career. Though he managed to stay on his feet for the rest of round 15, Frazier was declared winner by unanimous decision. In January 1974, however, Ali defeated Smokin' Joe in a non-title rematch. Getty Images Muhammad Ali: A life in pictures In October 1974, Muhammad Ali regained his title in what was to become of the biggest upsets in boxing history. Taking place in Congo, Ali’s fight against champion George Foreman was fittingly promoted as the Rumble in The Jungle. Almost no one gave Ali a chance of winning. Foreman and Ali became friends after the fight, and the movie When We Were Kings, a documentary of the fight in Zaire, even won an Oscar. Getty Images Muhammad Ali: A life in pictures The Thrilla In Manila was Ali's third, an final, fight against Joe Frazier. Leading up to the fight, Ali enraged Frazier through frequent insults and slurs, for example remarking: "It will be a killa ... and a chilla ... and a thrilla ... when I get the gorilla in Manila." It was a tedious fight, with both boxers battling each other into near incapacity. When Frazier's coach refused to allow Frazier to continue, Ali was declared winner by technical knockout. Later on, Muhammad Ali would declare that this was the closest to dying he had ever been, as well as stating that Joe Frazier was "the greatest fighter of all times, next to me." It also inspired the fight scene from Sylvester Stallone's 1976 Oscar-winning film Rocky. Getty Images Muhammad Ali: A life in pictures After the Thrilla In Manila, Ali beat Coopman as well as Jimmy Young and Richard Dunn. Following these wins, he staged an exhibition match with professional wrestler and Mixed Martial Artist Antonio Inoki (picture). This match would seriously jeopardise Ali's health, as both of his legs were bleeding after the fight, leading to an infection. He also suffered two blood cloths in his legs. Getty Images Muhammad Ali: A life in pictures As Ali had briefly lost the heavyweight title to Leon Spinks in February 1978, the Greatest fought a rematch in September, winning the title for a record third time (picture). Even after his retirement, Ali decided to return and win the title for an unprecedented fourth time, but lost against current champion Larry Holmes. As his coach, Angelo Dundee, refused to let Ali come out for the 11th round, it became Ali's only loss by anything other than a decision. Ali also lost his final fight against Trevor Berbick in 1981 by unanimous decision after ten rounds. Getty Images Muhammad Ali: A life in pictures Muhammad Ali is considered to be one of the greatest heavyweights of all time. In total, he won 56 of his 61 fights, 37 by KO. He was also the first person to win the heavyweight title three times. Consequently, he was named Sportsman of the Century by Sports Illustrated as well as Sports Personality of the Century by the BBC. Getty Images Muhammad Ali: A life in pictures Ali became known as a global champion of civil rights, including his friendship with Malcolm X Getty Images Muhammad Ali: A life in pictures His legacy continues to arouse interest up to this day, the most famous example being the biographical film Ali (2002). When Ali found out Will Smith was to play the young boxer, his first reaction was: "You ain't pretty enough to play me." Ali himself published an oral history, entitled Muhammad Ali: His Life and Times, in 1991. Getty Images Muhammad Ali: A life in pictures Muhammad Ali also received a vast number of honours and awards, such as the Spirit of America Award which called him the most recognized American in the world. In 1996, he had the honour of lighting the flame at the 1996 Summer Olympics in Atlanta. For his work with the US civil rights movement and the United Nations, Ali received the Presidential Medal of Freedom as well as the Otto Hahn Peace Medal in Gold. Getty Images Muhammad Ali: A life in pictures Muhammad Ali with his daughters Laila (9 months) and Hanna (2 years 5 months) in London in December 1978 Evening Standard/Getty Muhammad Ali: A life in pictures The boxer has been married four times, with his large family includes seven daughters and two sons. One of his daughters, Laila Ali, has also made herself a name as boxer, despite Ali's early comments against female boxing in 1978: "Women are not made to be hit in the breast, and face like that ... the body's not made to be punched right here. Get hit in the breast ... Hard ... and all that." Getty Images Muhammad Ali: A life in pictures Much of Ali's life after retirement was overshadowed by his suffering from Parkison's Syndrome disease, which was diagnosed in 1984. Nevertheless, he remained a beloved and active public figure right towards the end of his life. He continued to work for humanitarian causes, for example through his appointment as "U.N. messenger of Peace" to Afghanistan in November 2002. During these final years, Ali travelled on average more than 200 days per year. In 2005, he also opened the $50 million non-profit Muhammad Ali Center in Louisville, displaying his boxing memorabilia as well as focussing on core themes of peace, social responsibility, respect and personal growth. Getty Images Muhammad Ali: A life in pictures Muhammad Ali became a goodwill ambassador for the UN, seen here at Kabul airport in November 2002 during a three-day mission Getty Images Muhammad Ali: A life in pictures Muhammad Ali became known for his charity work including the annual Celebrity Fight Night, seen here on April 8, 2016 in Arizona Getty Images

Ron Tweel, an attorney for Ali's wife and estate, said he appreciated the president's comments, but that a pardon was "unnecessary".

"The US Supreme Court overturned the conviction of Muhammad Ali in a unanimous decision in 1971," he said in a statement. "There is no conviction from which a pardon is needed.”

Ali was born Cassius Clay, and changed his name after converting to Islam in the 1960s. He cited his religious beliefs in applying as a conscientious objector to the Vietnam War. In their 1971 ruling, the Court found that the government had failed to supply sufficient rationale for denying his conscientious objector status.

Ali served no jail time, and his criminal record was cleared. He died in 2016, at the age of 74.

Michael Parkinson interview shows Muhammad Ali'spowerful statement on racism

Mr Trump has pardoned six people since taking office. White House aides previously told the Washington Post that Mr Trump had become "fixated" on his ability to pardon – an essentially unchecked power of the presidency that stands out among other issues, such as the Russia investigation, that remain outside Mr Trump's control.

Mr Trump posthumously pardoned Jack Johnson, the first black heavyweight boxing champion, last month. Johnson was convicted in 1913 of transporting a white woman across state lines – a Jim-Crow era ruling that many have come to see as a grave injustice.

Just this week, the president pardoned Alice Marie Johnson, a woman serving a life sentence for a nonviolent drug offence. Her case was championed by reality star Kim Kardashian, who met with Mr Trump at the White House to discuss her case, among other issues.

Mr Trump said on Friday that he was considering some 3,000 more people for pardons. He added that he may start taking suggestions from pro athletes who kneel during the national anthem to protest racial injustice.

"I'm going to ask them to recommend to me people that were unfairly treated, friends of theirs or people that they know about and I'm going to take a look at those applications,” he said.

The president also recently claimed he has the power to pardon himself, if he is convicted of a crime stemming from the investigation of his campaign's ties to Russia. The suggestion was roundly rebuked by both Democrats and Republicans, who said doing so would set a dangerous precedent.