Pope Francis has defended his decision to reject French Cardinal Philippe Barbarin's resignation after he was convicted of covering up for a predator priest, saying the appeals process must run its course before a final decision is made.

Francis also explained why he rejected proposals by U.S. bishops to respond to the sex abuse scandal there, saying they neglected the spiritual dimension required for a true reform.

Francis referred to both cases during an in-flight news conference en route home Sunday from Morocco.

Francis' papacy has been thrown into turmoil by the eruption of the scandal on multiple continents and his own handling of cases. Currently, two of his cardinals — Barbarin and Australian Cardinal George Pell — have criminal abuse-related convictions hanging over them, though both are appealing.