Pope Benedict XVI urged an end to "religious hypocrisy" and "rivalry" in the Catholic Church as he donned his papal mitre for the last time at an emotional mass in St Peter's Basilica on Wednesday.
Pope Benedict XVI leads a mass for Ash Wednesday, opening Lent, the forty-day period of abstinence ahead of Easter at St Peter's basilica at the Vatican on February 13, 2013.
Wearing the purple robes of Lent -- a period of penitence for Christians before Easter -- the pontiff was conveyed through the basilica's vast nave on a mobile platform because of his growing infirmity.
Benedict urged the faithful to be sincere in their faith in his final mass as leader of the world's 1.2 billion Catholics before he becomes only the second pontiff to resign voluntarily in the Church's 2,000 years.
He condemned "religious hypocrisy" and called for an end to divisions, saying that "the face of the Church is sometimes marred by sins against the unity of the Church and divisions in the clergy", an apparent reference to the paedophilia or Vatileaks scandals plaguing the institution.
The pope also called for an end to "individualism and rivalry".
Earlier Wednesday, the frail pontiff was greeted by a standing ovation, applause and chants of "Benedetto" at his weekly audience with thousands of believers in a Vatican auditorium.
A prominent banner read: "Thank You, Holiness".
Benedict told the crowd he had taken his momentous decision "for the good of the Church".
"Keep praying for me, for the Church and for the future pope," he said, his voice full of emotion.
Wearing his workaday white cassock and skullcap, the pontiff said he could feel the faithful's love "almost physically in these difficult days".
The Vatican announced that cardinal electors -- the princes of the Church -- will meet on or in the days after March 15 to choose Benedict's successor.
"The beginning of the conclave cannot be before March 15," Vatican spokesman Federico Lombardi told a press conference. "We have to expect a conclave starting on the 15th, 16th, 17th 18th or 19th."
The secret conclave held in the Sistine Chapel under Michelangelo's famed ceiling frescoes -- deliberations that normally last a few days -- should produce a new pope in time for Easter.
Many ordinary Catholics have said they would like the new pope to be more in tune with the times after the traditionalist reigns of Benedict and his long-time predecessor John Paul II.
"I want someone who is youthful and with a youthful spirit who can be more flexible," said Ieva Tamosaityte, 25, a Lithuanian musician in the congregation at the pope's last mass.
"I would like future popes to retire when they get old too," she said, as staff in the basilica distributed photos of the outgoing pope.
Rumours have begun flying over front-runners to succeed Benedict, but no clear candidate has emerged yet and the decision will be up to the 117 elector cardinals.
While some hope that Africa or Asia could yield the next pontiff, others have tipped high-flying European or north American cardinals.
Benedict announced on Monday that he would resign because he no longer had the strength to carry out his duties.
Although the Vatican has denied specific health problems influenced his decision, it said Tuesday he had a secret operation to replace the batteries in his pacemaker three months ago.
Benedict will no longer be pope from 1900 GMT on February 28, after which as Lombardi put it "people will know they no longer have to go to him for questions regarding the Universal Church."
Shortly before the time runs out on his papacy, a helicopter will whisk Benedict away to the papal summer residence in Castel Gandolfo near Rome where he will live temporarily while his new permanent residence new permanent residence in the Vatican is being renovated.
Benedict will honour his existing engagements in the final days of his papacy with a few notable exceptions like meetings with Italian President Giorgio Napolitano and Prime Minister Mario Monti.
Benedict's resignation has eclipsed campaigning for the February 24-25 election in Italy, with analysts saying it could have a major impact on the outcome -- perhaps stopping scandal-tainted billionaire Silvio Berlusconi's rise in the polls.
At the Vatican, next week will be given over to a spiritual retreat which is sure to be dominated by jockeying among factions within the College of Cardinals over the choice of Benedict's successor.
The pope will hold his final general audience on February 27, this time a farewell event for all in St. Peter's Square, before retiring to a little-known monastery within Vatican walls, just a stone's throw away from his successor.
Asked about this unprecedented "cohabitation", Lombardi replied: "I think the successor and the cardinals will be very happy to have very close by the person who best of all can understand the spiritual needs of the Church."
Only one other pope has resigned voluntarily -- Celestine V in 1294 -- a humble hermit who stepped down after just a few months saying he could no longer bear the intrigues of Rome.
Cardinal Peter Appiah Turkson of Ghana, one of two Africans considered a "papabile", or eligible to become pope, has said the world may be ready for an African pontiff.
"Let God's will be done," Turkson told the Rome daily Il Messaggero in an interview.
The new pope will have to face up to growing secularism in the West, one of the Church's biggest challenges.
Benedict admonished Wednesday: "You cannot be Christians as a simple consequence of living in a society with Christian roots."
He added: "Even those born into a Christian family and given a religious education should... put God first in the face of the temptations that a secular culture presents all the time."