The pope's decision was taken on the basis of "some recently received information" about Bishop Juan Barros, the statement said.
Maltese Archbishop Charles Scicluna, who prosecuted cases involving predator priests for the Vatican's doctrinal body from 2002 to 2012, will travel to Chile to listen to witness statements.
Controversy over the 61-year-old Barros marred the pope's trip to Chile earlier this month, when he hugged and defended the bishop.
"The day they bring me proof against Bishop Barros, then I will speak," the pope said.
He later apologised to sexual abuse victims, acknowledging the word "proof" had hurt many people.
"I know there are many people who are abused and cannot prove anything."
However, he added that the Vatican had investigated the case and he was "convinced" of the bishop's innocence.
Francis named Barros to head the Osorno diocese in 2015 despite accusations by sex abuse victims that the prelate covered up the actions of disgraced paedophile priest Fernando Karadima.
Local Catholic groups in the diocese have demanded that Francis remove him.
Scicluna currently heads the Vatican tribunal that hears sex abuse appeals.
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