VATICAN CITY — In an extraordinary statement, the Holy See announced Thursday morning that Pope Francis had granted a leave of absence to Cardinal George Pell of Australia, a top Vatican official, adviser to the pontiff, and as of this week the highest-ranking Roman Catholic prelate to be formally charged with sexual assault, so that he could return to Australia to defend himself.

Speaking at the Vatican press office, Pell, wearing simple black clerical clothes and a dangling cross, read a statement declaring his innocence against the charges and what he called leaks by the news media and “relentless character assassination.’’

“I am looking forward finally to having my day in court,’’ Pell said as he sat next to a Vatican spokesman. “I am innocent of the charges. They are false. The whole idea of sexual abuse is abhorrent to me.’’

Australian police served the cardinal’s legal representatives hours earlier in Melbourne and have yet to reveal the details of the charges or the ages of the complainants.

At the Vatican, Pell, usually outspoken, stuck to a script, adding that he had kept Francis regularly informed over recent months.

“We talked about my need to take leave to clear my name,’’ said Pell, who in the past has insisted that he had the full backing of the pope. “So I’m very grateful to the Holy Father for giving me this leave to return to Australia.’’

As the faithful gathered outside St. Peter’s Basilica to hear Francis celebrate a special outdoor Mass in honor of St. Peter and St. Paul, Pell concluded, “The news of these charges strengthens my resolve — strengthens my resolve — and court proceedings now offer me an opportunity to clear my name and to return here back to Rome.’’

But it is not clear whether Pell will be coming back.

The charges come as many of Pell’s fellow prelates in the College of Cardinals have arrived in Rome from around the world for the elevation of five new cardinals by Francis on Wednesday. The pope has achieved global popularity for his emphasis on inclusiveness and mercy, but he has come under increased criticism for the slow pace and reported internal resistance to efforts to safeguard victims of sexual abuse by priests and protect children in the church.

Last month, the pope, who had promised “zero tolerance’’ for perpetrators of abuse, acknowledged a 2,000-case backlog of clerical sex abuse cases after the resignation in protest of an abuse survivor from a sex abuse advisory commission that the pope established in March 2014.