An estimated one million mourners crammed into and around St Peter's Square on Friday for a funeral mass expressing "joyful hope and profound gratitude" for the life of Pope John Paul II.

The pope "sees and blesses us," the officiating priest, German Cardinal Joseph Ratzinger, said to loud applause at the end of his homily, delivered over the plain cypress wood coffin on the windswept esplanade outside St Peter's basilica.

He spoke after the start of an almost three-hour requiem mass, one of the largest in history, broadcast live to hundreds of millions of television viewers around the world.

Ratzinger said that John Paul II, who died on Saturday aged 84 after years of debilitating illness, had borne "a burden which transcends merely human abilities."

Recalling how the pope had appeared at a window in the Vatican to bless believers on Easter Sunday, six days before his death, when he could no longer speak, the cardinal said: "Our pope never wanted to spare his own life, but gave himself unreservedly for Christ until his last moment ... now we can be sure that our beloved pope is at the window of God's house, where he sees and blesses us."

Tears for a "priest to the end"

At the start of the ceremony, the pope's coffin was carried by 12 officials from the basilica where his body had lain in state since Monday and was placed on a carpet in front of an altar specially erected for the purpose.

Vatican Swiss guards in yellow and purple uniforms and scarlet-plumed helmets stood by as Catholic prelates took their seats, bishops in purple, cardinals in red robes that whipped about in the breeze. An open red-bound New Testament was placed on top of the coffin, its pages flickering in the wind.

The vast crowd began by applauding the arrival of the casket, but many began weeping while the Sistine Chapel choir sang Gregorian chants.

The requiem mass ended at 12:30 pm, drawing lengthy applause from the mourners. After, as the coffin was borne aloft and headed back into St Peter's Basilica for burial, the crowd applauded a second time. And just before re-entering the basilica, it was held aloft and turned toward the square over which he had presided countless ceremonies in the past during his 26-year pontificate. Mourners wept and bells tolled as the coffin disappeared into the church a last time for burial in the crypt beneath.

"Our whole world will be different now," 18-year-old Beata from Poland, tears rolling down her cheeks, told Reuters. "I don't know what we will do without him to lead us."

And as even police struggled not to cry, people described this moment as "the best" of the past five days.

"It was the power of all the waiting in line and all the sleepless nights and all the people's love for the Pope crystallised in one moment," Francesco Podesta, a 22-year-old eonomics student from Genoa told Reuters.

Kings and commoners

The Italian news agency ANSA, citing security sources, said an estimated 300,000 people had gathered on St Peter's Square itself and a further 700,000 in the surrounding streets, watching the mass on huge video screens.

The funeral brought together royalty such as Prince Charles of England and at least 70 heads of state such as German Chancellor Gerhard Schröder with millions of ordinary mourners.

Among other leaders who attended were UN Secretary General Kofi Annan and Afghan President Hamid Karzai, one of a number of Muslim leaders due to attend, who hailed the pope as "a man with concern for all human beings."

Also present was US President George W. Bush, who clashed with the pope over the US-led war on Iraq but who called him earlier this week "one of history's great moral leaders."

Millions of pilgrims came from John Paul II's homeland of Poland including President Aleksander Kwasniewski and his predecessor Lech Walesa, whose Solidarity trade union movement was inspired by John Paul II to resist the then-communist regime in power in Poland.

It contributed to the fall of communism throughout eastern Europe, in what historians say is one of the pope's greatest legacies.

"Going perfectly"

Since the pope's death last Saturday, an unending sea of humanity has filed past his body as it lay in state in the basilica, dressed in red and white vestments. After the deluge in Rome, Italian officials initially pleaded for mourners to stay out of Rome. By Friday, they changed their tune.

"Everything is going perfectly," Guido Bertolaso, the government-appointed commissioner in charge of the arrangements, told AFP.

Hundreds of policemen were deployed just on the square and the main artery to the basilica while several thousand officers patrolled the neighbourhood.

As security was buttoned down, Rome's second airport, Ciampino, was closed to commercial flights until midnight Friday, and a no-fly zone over the city itself was being enforced by Italian and NATO aircraft.

Over 10,000 police, military and paramilitary officers, including hundreds of marksmen, were being deployed. Teams with dogs patrolled.

Police said cars would be banned throughout Rome all day on Friday and that all public offices and schools would close.

In illustrious company

Before the start of the funeral, Vatican officials said that the pope's body had been placed in a simple cypress-wood coffin inside the basilica. After the mass, the coffin would be placed inside a zinc coffin, then into an oak casket, for burial in the crypt below the church.

John Paul II will be buried alongside some of his illustrious predecessors, in a tomb marked only by a simple slab in stark contrast to the ornately sculpted tombs in which many of his predecessors are interred. The slab will be inscribed simply with the late pontiff's name in Latin, Joannes Paulus II, and the years of his life, 1920-2005.

The pope's only instruction concerning his burial was that he be interred in the ground, Vatican spokesman Joaquin Navarro Valls said this week, also laying to rest speculation that the pope would request to be buried in his native Poland.

The late pontiff will be buried at the site left vacant by the coffin of Pope John XXIII, who died in 1963 but who was transferred to a Vatican chapel when he was beatified in 2000. John Paul II's remains will lie between the tomb of Paul VI and that of Christine of Sweden, the eccentric queen who abdicated in 1655 to convert to Catholicism.

Nearby is the site where the first pope, Saint Peter, is believed to have been buried. Next to Benedict XV lies the late pope's immediate predecessor John Paul I, who died after a brief 33-day papacy in 1978.