Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

A top American cardinal has demanded answers to allegations that Pope Francis helped cover up clerical sexual abuse as the scandal engulfing the Roman Catholic Church has exposed bitter divisions within its senior hierarchy.

Cardinal Daniel N. DiNardo, the archbishop of Galveston-Houston in Texas and president of the U.S. Conference of Catholic Bishops, said the allegations by Archbishop Carlo Maria Viganò in a letter released over the weekend deserved responses that are “conclusive and based on evidence.”

“Without those answers, innocent men may be tainted by false accusation and the guilty may be left to repeat sins of the past,” DiNardo said in a statement.

He also called for a meeting with the pope to "make reporting of abuse and misconduct by bishops easier, and improve procedures for resolving complaints against bishops."

Marco Tosatti, an Italian journalist and veteran Vatican watcher, said that he helped Viganò, a former Vatican ambassador to the U.S., write the letter and that the prelate’s reason for publishing the text was to “clean the church” and to “clean his conscience.”

The call for action came as the Vatican struggled to contain the fallout from the 11-page letter that alleges that Francis knew about sex abuse allegations against former Cardinal Theodore McCarrick for years, but chose to cover up the charges and promote him before accepting his resignation last month.

Michael Walsh, a historian on the papacy and the editor of the Oxford Dictionary of Popes, said tensions between reformists like Francis and conservatives like Viganò have been bubbling up since Francis was elected pope in 2013.

Francis, he says, was in part elected on an agenda to reform the Curia, which serves as a form of governmental cabinet whose members handle both administrative and judicial functions for the church at large. But the pope's efforts have met resistance from a group of conservative cardinals and bishops who are opposed to policies such as allowing divorced and remarried people receive Holy Communion.

“The war within the Vatican has been going on for a long time,” Walsh said. “What’s new is the degree of discontent and particularly that people are vocalizing it and articulating it.”

Cardinal Daniel DiNardo, president of the United States Conference of Catholic Bishops, speaks at a news conference during their annual fall meeting in Baltimore. Patrick Semansky / AP file

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

In the letter, Viganò said Pope Benedict XVI imposed sanctions on McCarrick in 2009 or 2010, ordering him to withdraw to a lifetime of prayer and penance, but that Francis chose to rehabilitate him, "cover" for him and elevate him to “trusted counselor.”

Viganò also identifies by name the cardinals and U.S. archbishops who he claims were informed about the McCarrick affair — a shocking expose for a Holy See official to make. NBC News could not confirm the letter's claims and Viganò offered no evidence to back up his allegations.

The letter came midway through Francis’s highly charged weekend visit to Ireland, which was dominated by the church’s sex abuse scandal. It also came days after Francis begged forgiveness after a grand jury report that found that more than 1,000 children had been sexually abused by “predator priests” in Pennsylvania for decades.