WASHINGTON - In a hallowed place where popes have prayed and pilgrims have flocked, mourners gathered Saturday at the nation's largest Catholic church to pay their final respects to Supreme Court Justice Antonin Scalia.

Scalia's sons and sons-in-law served as pallbearers to carry his flag-draped casket into the Basilica of the National Shrine of the Immaculate Conception for a funeral Mass honouring the late jurist who died unexpectedly last weekend.

Dignitaries including Vice-President Joe Biden, former Vice-President Dick Cheney, members of Congress and all eight sitting justices of the Supreme Court were among those attending.

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Scalia's casket arrived at the basilica after he lay in repose at the Supreme Court on Friday, where thousands of visitors came to honour one of the country's most influential conservatives.

One of Scalia's nine children, the Rev. Paul Scalia, led the Mass and delivered the homily, describing his father as a man devoted to God, country and family.

Mixing humour into the homily, the younger Scalia said his father sometimes forgot his children's names or mixed them up but he excused him because there were nine of them.

He recalled how his father reacted once after accidentally standing in his son's confessional line. The justice said: "'Like heck if I'm confessing to you."' Paul Scalia joked that "the Roman collar was not a shield against his criticism."

Several federal judges who are considered possible replacements for Scalia also were at the funeral Mass, including Judges Sri Srinivasan and Patricia Millett and Chief Judge Merrick Garland, all of the U.S. Court of Appeals for the District of Columbia Circuit.

President Barack Obama did not attend, despite criticism from some Republicans. He and first lady Michelle Obama were among the more than 6,000 people who paid tribute to Scalia at the Supreme Court on Friday. Scalia's flag-draped casket rested on a funeral bier that first held President Abraham Lincoln's casket after his assassination.

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White House spokesman Josh Earnest pointed to Biden's personal relationship with Scalia's family and said Obama's decision about the Mass was a "respectful arrangement" that took into account his large security detail.

Scalia, 79, died last weekend at a remote Texas ranch after spending nearly three decades on the high court. Burial plans have not been announced.

Republican presidential hopeful Ted Cruz interrupted his campaign ahead of Saturday's South Carolina primary to attend the Mass. The Texas senator has been among those urging the Senate not to consider replacing Scalia until after the November election. Obama has insisted that he will nominate a successor.

Washington Archbishop Donald Cardinal Wuerl drew chuckles when he told the massive crowd at the funeral Mass that he would keep opening remarks brief "in keeping with your desire to have a simple parish family Mass."

Wuerl expressed to Scalia's family and mourners "our heartfelt sympathy at the loss of your husband, your father, grandfather and friend."

Leonard Leo, executive director of the Federalist Society, a conservative legal group. read a passage from the Old Testament's Book of Wisdom. Supreme Court Justice Clarence Thomas, who shared Scalia's conservative judicial leaning, read a passage from the New Testament's Book of Romans.

Three popes have visited the basilica: Pope John Paul II in 1979, Pope Benedict XVI in 2008 and Pope Francis last year.