We pray for those priestly brothers of ours who have not lived up to the commitments they made when they were ordained or who are going through a period of difficulty and crisis

Pope John Paul II

The 81-year-old remained seated and allowed the Vatican's Secretary of State, Cardinal Angelo Sodano, to symbolically cleanse the feet of 12 priests. The act commemorates Christ's humility towards his apostles.

The Pope sat slightly bent in his chair, reciting some prayers.

The pontiff suffers from Parkinson's Disease, as well as an arthritic right knee.

In a sermon, which he gave while seated, the Pope made reference to the wave of sex scandals now rocking the Roman Catholic Church.

"We pray for those priestly brothers of ours who have not lived up to the commitments they made when they were ordained or who are going through a period of difficulty and crisis," he said.

Ailing

The Pope's health has been declining steadily since the early 1990s, when symptoms of Parkinson's first appeared. His left hand now trembles uncontrollably.

He had a colon tumour removed in 1992, dislocated his shoulder in 1993, broke his femur in 1994, and had his appendix removed in 1996.

He walks with a cane and for the past two years has been pushed up the aisle of St Peter's Basilica on a wheeled platform.

The Pope used a special wheeled platform

Fresh concerns over his health were raised earlier this week when John Paul II decided not to celebrate Palm Sunday mass in St Peter's Square. Instead, he chose to watch from his throne while the Vicar of Rome Cardinal Camillo Ruini led the ceremony.

Thursday marked the start of a gruelling four-day series of Easter ceremonies, as Christians celebrate the holiest week of their calendar.

On Good Friday, the Stations of the Cross ceremony takes place.

This traditionally requires the pope to carry a 3kg replica cross along 15 stations marking Christ's journey to crucifixion.

But declining health has meant that every year, the Pope is able to take fewer steps.

Last year, he only carried the cross for the last station.