VATICAN CITY — For the first time since the election of Pope Francis two days ago, the Vatican on Friday formally defended him from accusations that, decades ago, in the so-called Dirty War in his home country of Argentina, he knew about serious human rights abuses but did not do enough to halt them.

Rev. Federico Lombardi, the Vatican spokesman, said there had “never been a credible accusation against him” relating to the period in the 1970s when he was the superior of the Jesuit order in Argentina.

Indeed, “there have been many declarations of how much he did for many people to protect them from the military dictatorship,” Lombardi said in a statement. “The accusations belong to the use of a historical-social analysis of facts for many years by the anti-clerical left to attack the church, and must be rejected decisively.”

‘No compromise’

Pope Francis, the former Cardinal Jorge Mario Bergoglio of Buenos Aires, was elected by fellow cardinals Wednesday, and much of his behavior since then has seemed to indicate a shift of tone at the Vatican to a more humble and frugal approach.

When he addressed cardinals Friday, for instance, he spoke frequently without notes, addressing them as “Brother Cardinals” rather than as the more usual “Lord Cardinals,” and the Vatican press office highlighted other shows of modesty and lack of formality since his election.

But the question of his past has never been far below the surface, rekindling accusations relating to a conflict in which as many as 30,000 people disappeared or were tortured or killed by the dictatorship.

At a news conference Friday, Lombardi repeated assertions by a prominent human rights campaigner that there had been “no compromise by Cardinal Bergoglio with the dictatorship.”

The debate has simmered in Argentina, with journalists there publishing articles and books that appear to contradict Francis’ account of his actions. These accounts draw not only on documents from the period, but also on statements by priests and lay workers who clashed with Francis.

After the church had denied for years any involvement with the dictatorship, he testified in 2010 that he had met secretly with Gen. Jorge Videla, the former head of the military junta, and Adm. Emilio Massera, the commander of the navy, to ask for the release of two kidnapped priests.

Lobbied military rulers

The following year, prosecutors called him to the witness stand to testify on the military junta’s systematic kidnapping of children, a subject he also was accused of knowing about but failing to prevent.

In an interview published by an Argentine newspaper in 2010, Francis said he had helped hide people being sought for arrest or disappearance by the military because of their political views, had helped others leave Argentina and had lobbied the country’s military rulers directly for the release and protection of others.

The renewed discussion of the case intruded into a day when Francis offered warm praise to his predecessor, Benedict XVI, saying that his nearly eight years as leader of the world’s 1.2 billion Roman Catholics had “lit a flame in the depths of our hearts.”

Speaking to the church’s cardinals, he urged them to persevere and find ways to spread word of their faith around the world.

Brief stumble

“Let us not give in to pessimism, to that bitterness that the devil offers us every day,” he said. He offered no direct allusion to the myriad challenges facing the Vatican from a series of sexual abuse and financial and other scandals that swamped much of Benedict’s papacy.

According to the officials, Francis frequently extemporizes, making it more difficult for the papal press office to deliver texts of addresses like Friday’s.

“That’s the cost of having such spontaneity,” said Rev. Thomas Rosica, a Vatican spokesman.

There was one clearly unchoreographed moment. Francis, 76, stumbled briefly as he greeted the dean of the College of Cardinals, Angelo Sodano, but swiftly recovered.

The pope also sent a message Friday to Rome’s chief rabbi, saying he wished to pursue closer ties between Catholics and Jews.

“I hope very much to be able to contribute to the progress in relations between Jews and Catholics” the pope said.