Pope Francis on on Tuesday accepted the resignation of a Kansas City, Missouri, bishop who for years had remained in office despite having been convicted of a sex-abuse cover-up, the Washington Post reported.

Robert Finn, the first U.S. bishop to be criminally convicted in such a cover-up, received two years of probation in 2012 for failing to inform authorities when a computer technician found hundreds of images of child pornography on a priest's laptop, the newspaper detailed.

"The Holy Father has accepted the resignation from the pastoral government of the diocese of St. Joseph-Kansas City, Mo. (United States), presented by His Excellency Bishop Robert Finn," the Vatican said in a brief statement.

Vatican Radio, an official Church media outlet, said the statement cited a paragraph of canon law that urges a bishop to present his resignation if he becomes "less able to fulfill his office because of ill health or some other grave cause."

Finn's removal is "a good step but just the beginning," said Anne Doyle, the co-director of BishopAccountability.org, a watchdog group that documents the Catholic Church's abuse crisis. The Vatican's one-light announcement, however, was insufficient, she told CNN.

"The pope must show that this decision represents a meaningful shift in papal practice - that it signals a new era in bishop accountability," Doyle demanded. "What no pope has done to date is publicly confirm that he removed a culpable bishop because of his failure to make children's safety his first priority. We urge Pope Francis to issue such a statement immediately."

Tried by a judge instead of by jury because prosecutors wanted to protect the young victims' anonymity, Finn was convicted over his diocese's dealings with Shawn Ratigan, an Independence, Missouri, priest who had pleaded guilty to five child pornography charges.

"I truly regret and am sorry for the hurt these events have caused." the bishop told CNN affiliate KCTV at the time, the news channel recalled.

Francis decided that for now, Finn will be replaced by Kansas Archbishop Joseph Naumann, who will act as the Kansas City diocese's apostolic administrator until the pontiff appoints a permanent bishop.