The Vatican has denied accusations by some critics in Argentina that Pope Francis stayed silent during systematic human rights abuses by the former military dictatorship.
Vatican spokesman Father Federico Lombardi told reporters the accusations "must be clearly and firmly denied".
He said: "They reveal anti-clerical left-wing elements that are used to attack the church."
Critics of Jorge Bergoglio, the former Archbishop of Buenos Aires, allege he failed to protect priests who challenged the dictatorship earlier in his career, during the 1976-1983 "dirty war".
They say he has said too little about the complicity of the church during military rule.
The allegations refer to a time before Fr Bergoglio became a bishop, when he was leader of the Jesuits in Argentina.
Two priests kidnapped by the military government alleged Fr Bergoglio did not protect them.
"There has never been a concrete or credible accusation in his regard. Argentinian justice interrogated him once ... but he was never charged with anything," Fr Lombardi said.
"He documented his denials of the accusations against him. There are also many declarations that show how Bergoglio tried to protect many people in his time during the military dictatorship. His role is very clearly noted.
"When he became bishop, he promoted the whole cause of reconciliation in the Church of Argentina."
Some human rights activists in Argentina have questioned the moral credentials of Pope Francis since his election on Wednesday, because of the allegations over the dirty war period.
The Argentinian church's reputation was tarnished by links between some high-ranking Catholic clergymen and the military junta that kidnapped and killed up to 30,000 leftists.
Cameron says Pope is wrong on Falklands
Meanwhile, British Prime Minister David Cameron has said Pope Francis was wrong to say last year that Britain had "usurped" the Falkland Islands from Argentina.
He said he respectfully disagreed with the new Pontiff.
Argentinian media quoted Jorge Bergoglio saying at a mass last year to mark the 30th anniversary of the war over the islands between Britain and Argentina that the territory had been "usurped".
In 2010, he was quoted as saying it was "ours".
When asked whether he agreed with the former archbishop of Buenos Aires on the issue, Mr Cameron said: "I disagree with him, respectfully."
Mr Cameron said that residents of the South Atlantic islands had made it clear in a referendum held earlier this week that they wanted to remain under British rule.
"There was a pretty extraordinarily clear referendum in the Falkland Islands," Mr Cameron told a news conference in Brussels, where he was attending a European Union summit.
"That is a message to everyone in the world that the people of these islands have chosen very clearly the future they want. That choice should be respected by everyone."
Argentina, 500km to the west of the Falklands, has claimed the South Atlantic archipelago for almost 200 years and in 1982 invaded the islands only to be repelled in a 74-day war with Britain.
Diplomatic rows between Britain and Argentina have escalated in recent months, with Britain resisting calls by Argentina's President Cristina Fernandez to renegotiate the sovereignty of the islands.
Elsewhere, the Presbyterian Church in Northern Ireland has welcomed the election of Pope Francis.
In a statement, the Moderator of the Presbyterian Church wished the Argentine Pontiff well, describing him as a champion of the poor and the oppressed.
The Reverend Roy Patton said this, together with his simple lifestyle, indicated that he was a humble man.
Pope sends St Patrick's Day message
Pope Francis has sent a greeting to the people of Ireland to mark St Patrick's Day.
Papal Nuncio to Ireland Archbishop Charles Brown delivered the message to President Michael D. Higgins this afternoon.
The message is one of the first that the newly-elected Pope has sent.
In the communication, Pope Francis said that he wished to send greetings to President Higgins and his fellow citizens on the happy occasion of Ireland's national day.
He said that at the beginning of his pontificate he "commended the nation to the powerful intercession of St Patrick".
Pope Francis said he wanted to assure the nation of his prayers for what he described as "the beloved people of Ireland" so that they may enjoy peace and prosperity.