Who are the three bishops under Vatican review for sex abuse?

Pope Francis has warned he has "zero tolerance" for child sex abuse in the Catholic church and revealed that the Vatican is currently investigating three bishops.

But the pope did not name names, and Vatican officials on Tuesday declined to comment.

So who are the three bishops under Vatican investigation? The speculation is that the pope likely was referring to three clerics:

• Scottish Cardinal Keith O'Brien, who resigned in February 2013 on the eve of the conclave that elected Francis. O'Brien later admitted that "there have been times that my sexual conduct has fallen below the standards expected of me as a priest, archbishop and cardinal."
• Polish Archbishop Josef Wesolowski, who was accused of child abuse in Poland and during his period as papal nuncio in the Dominican Republic until his dismissal in August;
• Chilean Bishop Cristian Contreras, who has been accused of abuse by other priests in his diocese.

Francis made his comments to journalists aboard his return flight to Rome on Monday as he wrapped up his first visit to the Middle East.

"Sexual abuse is such an ugly crime ... because a priest who does this betrays the body of the Lord," the pope said. "This is very serious. It is like a satanic Mass."

When the pope said one of the three bishops had been found guilty, that led to immediate speculation he was referring to Bishop Robert Finn from Kansas City-St. Joseph, Mo., who was convicted in 2012 for failing to report a priest for child pornography. But so far, there is little indication Finn -- who remains in office -- is facing Vatican review.

"Finn deserves to be fired or at least demoted because of his deceit, recklessness, callousness and selfishness in pedophile priest cases," said the Chicago-based Survivors Network of those Abused by Priests (SNAP), which represents around 18,000 victims worldwide, saying SNAP isn't aware "of another bishop who has been convicted of endangering kids who is still on the job."

But Francis did not single out Finn -- or any other bishop -- by name.

"At the moment, there are three bishops under investigation: One has already been found guilty and we are now considering the penalty to be imposed," the pope said during the nearly hourlong media conference. "There are no privileges. We must go forward with zero tolerance."

The 77-year-old pontiff also announced he would meet with a group of sex abuse victims for the first time at the Vatican early next month.

Francis said he would meet with eight victims from Germany, England and Ireland. Boston Cardinal Sean O'Malley, who heads a commission looking at new ways of dealing with the crisis, will be there. The timing and details of the meeting are still being worked out.

SNAP said the pope's comments changed nothing, noting that Francis will be the third pope to meet abuse victims.

"No child rape will be prevented, no abuse cover-up will be prevented and no predator priest will be exposed by anything the pope said today or will do next month," Joelle Casteix, western regional director of SNAP, said in a statement. "His upcoming and self-serving meeting with victims is more of what we've seen for decades -- more gestures, promises, symbolism and public relations."