VATICAN CITY — Reacting with unusual swiftness, the Vatican on Friday rejected any suggestion that Pope Francis of Argentina was implicated in his country’s so-called Dirty War during the 1970s, tackling the issue just two days after the pontiff’s election.

On a day when Francis delivered a warm address to his cardinals and continued to project humility, the Vatican seemed intent on quickly putting to rest questions about the pope’s past, dismissing them as opportunistic defamations from anticlerical leftists. The swift response contrasted with past public relations challenges during the papacy of Pope Benedict XVI, when the Vatican often allowed criticisms to linger without rebuttal.

“There has never been a credible accusation against him,” said the Rev. Federico Lombardi, the Vatican spokesman, adding that such charges “must be rejected decisively.” On the contrary, he said, “there have been many declarations of how much he did for many people to protect them from the military dictatorship.”

The charges derive from the pope’s days as the provincial, or leader, of Argentina’s Jesuits in the 1970s, a time of conflict in his country when the dictatorship tortured, killed or “disappeared” as many as 30,000 people.