* Pope leads new cardinals at joint Mass in St. Peter's Basilica
* For second straight day, Francis warns prelates of worldly temptations
* Francis calls for unity, simplicity, service (Adds comments in at noon blessing, paragraphs 11-12)
By Philip Pullella
VATICAN CITY, Feb 23 (Reuters) - Pope Francis urged cardinals, who make up the top echelon of the Roman Catholic Church, on Sunday to shun the intrigue, gossip and cliques typical of a royal court.
Since his election nearly a year ago, Francis has often told his top aides not to live or behave like a privileged class. The eight-year papacy of his predecessor, Benedict, was marked by mishaps and missteps, which were often blamed on a dysfunctional Vatican bureaucracy and intrigue befitting a Renaissance court.
On Sunday, Francis celebrated a mass with 18 of the 19 new cardinals who were elevated to that rank on Saturday. One could not attend because of illness.
"A cardinal enters the Church of Rome, not a royal court," Francis said in his sermon, welcoming the men into the elite group that help him run the Church in the Vatican and around the world.
"May all of us avoid, and help others to avoid, habits and ways of acting typical of a court: intrigue, gossip, cliques, favouritism and preferences," he said during a solemn ceremony in St. Peter's Basilica.
"Jesus did not come to teach us good manners or to behave as if we were at a social gathering," Francis told them.
It was the second consecutive day that Francis had warned cardinals to shun worldly temptations in the corridors of clerical power, either at home or in the nerve centre of the 1.2 billion-member Church.
At the induction ceremony on Saturday, which was attended by ex-pope Benedict, Francis urged the cardinals to avoid rivalries and factions. It was the first time Francis and Benedict, who resigned on Feb. 28, 2013, had been together for a liturgical celebration.
The "Vatileaks" scandal, in which Benedict's butler was arrested for leaking the pope's private papers to the media, alleged corruption in the Holy See, something the Vatican denied.
UNITED IN SIMPLICITY AND SERVICE
He asked the new cardinals to remain united among themselves and with him as they advise and help him run the Church in the Vatican and beyond in a spirit of simplicity and service.
Later, addressing tens of thousands of people in St. Peter's Square for his Sunday blessing, Francis said Catholic leaders should "not consider themselves holders of special powers or bosses, but place themselves at the service of the community".
They should be "good servants, not good bosses," he said.
Since his election last March as the first non-European pope in 1,300 years, Francis has attempted to infuse the Vatican and the Church with his simple style.
Last month, when he announced the names of the new cardinals, he quickly followed up with a letter to each asking that they not see their appointment as a promotion and not to waste money holding celebratory parties.
Francis, who has called for a "poor Church, and for the poor", has set the example himself. He has opted to live in a simple boarding house rather than the Apostolic Palace, and travels in a blue Ford Focus rather than a luxury car.
Cardinals are the pope's closest advisers in the Vatican and around the world. Apart from being Church leaders in their home countries, those who are not based in the Vatican are members of key committees in Rome that decide policies that can affect the lives of all Roman Catholics.
Sixteen of the new appointees are "cardinal electors" who join 106 existing cardinals who are also under 80 and thus eligible to enter a conclave to elect a pope from among their own ranks.
They come from Italy, Germany, Britain, Nicaragua, Canada, Ivory Coast, Brazil, Argentina, South Korea, Chile, Burkina Faso, the Philippines and Haiti. The non-electors come from Italy, Spain and Saint Lucia. (Reporting By Philip Pullella; Editing by Larry King)