Updated

The Vatican said Thursday that Usama bin Laden's accusation that Pope Benedict XVI had played a role in a worldwide campaign against Islam is "baseless," as the CIA said it was "confident" that the voice on the tape is in fact the terror leader's.

The Vatican spokesman, the Rev. Federico Lombardi, said it was not surprising that bin Laden had mentioned the pope in a new audiotape posted late Wednesday on a militant Web site -- which the CIA believes is authentic, a U.S. intelligence official told Reuters.

"He was already named in previous messages," Lombardi said in a telephone interview. "It is absolutely baseless (to accuse) the pope of contributing to a lack of respect toward Islam" and its prophet, Muhammad, Lombardi said.

In the tape, bin Laden warned of a "severe" reaction for Europe's publication of cartoons of the prophet and said they were part of a "new Crusade" against Islam in which Benedict had played a "large and lengthy role."

Lombardi noted that the pope and the Vatican have criticized the cartoons on several occasions.

In 2006, after the caricatures were first published in a Danish newspaper, the Vatican said the cartoons represented an "unacceptable provocation," and that the right to freedom of expression "cannot entail the right to offend the religious sentiment of believers."

The pope later said religious symbols must be respected, but he also condemned as unjustified the violent protests in Muslim countries that followed the publication of the cartoons.

Benedict has recently taken steps to improve relations with moderate Islam.

In November he will meet Muslim religious leaders for a seminar that was organized after 138 Muslim scholars and intellectuals wrote to Benedict and other Christian leaders to encourage Christians and Muslims to develop their common ground of belief in one God.

In a 2006 speech in Germany that angered many in the Muslim world, Benedict cited a medieval text that characterized some of the teachings of the Prophet Muhammad as "evil and inhuman," particularly "his command to spread by the sword the faith."

The pope later said he was "deeply sorry" about the reactions his remarks sparked and stressed that they did not reflect his own opinions.