Vatican City - The Vatican named as the date of Pope John Paul II's funeral as thousands of mourners gathered in a sun-filled Saint Peter's Square to pay their last respect when his body goes on public view.
Cardinals who convened Monday for the first time since the pontiff's death also confirmed that he would be buried in St Peter's Basilica, in keeping with tradition, rather than his native Poland.
Announcing details of the funeral arrangements, Vatican spokesman Joaquin Navarro-Valls said the requiem mass at 10:00 am (0800 GMT) would be celebrated by Cardinal Joseph Ratzinger, the Vatican's doctrinal enforcer and a possible successor.
The funeral is expected to draw hundreds of millions of television viewers worldwide as well as up to two million mourners in Rome and around 200 state and religious leaders.
However, Navarro-Valls gave no information on when the cardinals would meet in closed-door conclave to begin the process of electing a successor.
Under Vatican rules, the conclave cannot meet until at least 15 days after the pope's death late Saturday, which would be April 17.
As he spoke, mourners gathered in their thousands ready for the pope's body to go on public view in the basilica later Monday.
Black-clad Swiss guards, traditional guardians of the Vatican, stood watch as the mourners flocked onto the square. Barriers have been set up to contain the crowds, with hundreds of thousands of people likely to file solemnly past the body.
"It is a sign that he was a man of God, to see all these people from every religion, every race, every country coming to see him," Italian priest Carmine Pellegrino said.
Navarro-Valls said the basilica would remain open practically all day and night until the funeral, closing only for a few hours overnight for cleaning.
Around the world, Christians and people of other faiths prayed, mourned and paid tribute to a pope seen as transcending religious barriers.
In Asia, flags were lowered to half mast from Hindu India to Australia and Buddhist Thailand to the staunchly Catholic Philippines.
In his native Poland and across Europe, in the Middle East, Africa and the Americas, special masses were said, vigils kept and candles burned.
The pope's embalmed body was to be carried in a solemn procession from the Apostolic Palace, the papal residence where he died, across St Peter's Square and into the basilica, one of the world's largest churches, where it was to be laid before the altar.
The procession was to begin at 5:00 pm with the public being allowed into the basilica three hours later.
The Polish embassy in Rome said Polish President Aleksander Kwasniewski and Lech Walesa, founder of the Solidarity trade union movement, would attend the funeral.
The pope's support for the union is credited with helping end communism in Poland, and later across eastern Europe.
US media said President George W. Bush, a devout Christian who clashed with the pope over the Iraq war, was also expected, although there was no immediate confirmation from the White House.
No US president has ever attended a pope's funeral.
Security will be tight -- Italian authorities are to deploy more than 6,400 police to ensure security, with the ANSA news agency saying air force aircraft would enforce a no-fly zone over the capital.
The pope's body has already been laid out in the Apostolic Palace so that cardinals, officials and Vatican employees can pay their respect following his 26-year pontificate.
He was pictured on television dressed in red and white robes and a white mitre, a serene expression on his face, his pale hands clutching a crucifix.
Amid the grieving and commemorations, there was speculation as to who will succeed John Paul II.
Australian Cardinal George Pell reassured fellow traditionalists that the Vatican conclave would choose another figure who would hold to the late pope's staunch conservative line on theological issues.
"I'm quite sure the general line -- fidelity to basic Catholic teachings -- is absolutely unassailable," he told ABC radio.
Swiss Cardinal Henri Schwery said he wanted the next pontiff to have field experience rather than being a Vatican official, saying the modern world made it essential for the pope to play a diplomatic and political role.
Meanwhile in Britain, aides to heir to the throne Prince Charles refused to rule out changing his plan to marry his longtime partner Camilla Parker Bowles on Friday, the same day as the funeral.
His Clarence House office said that it remained "sensitive to events that are happening elsewhere around the world."
In France, leading French left-wingers sparked a row after criticising the government of President Jacques Chirac for lowering flags on public buildings in tribute to the pope, which they said breached secular principles.