Pope John Paul II has inaugurated the Roman Catholic Church's Holy Year by opening the Holy Door in St Peter's Basilica in Rome at a midnight mass.

A procession of laymen, cardinals, bishops and other clergy made their way from the right side of the basilica to its atrium where the Holy Door is located.

In a gesture to be repeated by bishops in 5,000 churches throughout the world, John Paul II spoke the traditional command in Latin: "Aperite mihi portas justitiae" - or Open to me the doors of Justice.

He gently pushed the large, two-part bronze door, and two uniformed ushers on the other side then pulled it completely open.

The year 2000 marks the transition from the second to the third millennium after Christ's birth.

The Great Jubilee, as the Vatican calls it, is a whole year of pilgrimages, special masses, concerts of sacred music and Papal audiences.

Millions of pilgrims are expected to visit the Italian capital during the Holy Year.

Admission to the opening ceremony in St Peter's Basilica has been limited to only 7,000 pilgrims, with some 50,000 others following the service outside in St Peter's Square on huge television screens.

In addition, television viewers around the world have been watching the Pontiff as he opened the Holy Door, which is kept bricked up and closed except during Holy Year.

Frail health

After opening the door, he then began to celebrate the first Mass of Christmas Day, commemorating the anniversary of Christ's birth.

The Pope will be 80 years old next May, and he suffers from a form of Parkinson's Disease.

Due to his frail health, he will rest after celebrating Midnight Mass and won't appear again in public until midday on Christmas Day.

Then he will give his solemn blessing, "Urbi et Orbi", to the city of Rome and to the world.

Holy Land visit

Joaquin Navarro, one the Pope's chief aides who is also a doctor, is not too concerned about John Paul II's health.

"The very concept of health is something which is relative," said Mr Navarro.

"Most doctors around the world say somebody is healthy when he can she can perform the primary object of his or her life.

"From that point of view, I'm sure the Pope is healthy enough!

"This year will be very demanding for him, and I'm sure he will do all the things that he wants to do for the sake of the Jubilee."

Next March, as part of the Jubilee celebrations, the Pope will visit the Holy Land.

It will be the first time a Roman Pontiff has been to Jerusalem and to Bethlehem since the visit of Paul VI in 1964.