Pope Benedict XVI has sent a letter to Roman Catholic bishops around the globe saying the Vatican made "mistakes" in its handling of the recent lifting of the excommunication of a Holocaust-denying cleric, a newspaper reported Wednesday.

The Vatican press office confirmed a letter would be released Thursday, but gave no details on what it says about British-born Bishop Richard Williamson.

Benedict's lifting of the Williamson excommunication drew widespread criticism because of the bishop's appearance in a January interview during which he denied that 6 million Jews were killed by the Nazis. He told Swedish TV about 200,000 or 300,000 were murdered but none were gassed.

The Rome newspaper Il Foglio said the pope writes that the Vatican should have been aware of the statements, which were being carried on the Internet. Benedict also faults the Vatican for not explaining its actions on Williamson in a "sufficiently clear" way, the conservative-leaning daily said.

According to the ANSA news agency, Benedict defends himself by saying that the overlapping of the rehabilitation of Williamson and the interview was "unpredictable." The pope also echoed previous statements, saying the lifting of the excommunication was a "gesture of mercy."

The bid to explain the case comes only a few days after Benedict confirmed that he would visit Israel in May as part of a pilgrimage to the Holy Land.

Vatican-Jewish relations already were complicated by the church's defense of World War II Pope Pius XII, whom Benedict has hailed as a "great" churchman. Some Jewish groups and others say Pius didn't do enough try to stop the Holocaust during World War II, while the Holy See insists he used quiet diplomacy to try to help Jews.

Williamson gave the interview shortly before his excommunication was lifted by Benedict, who is eager to bring ultraconservative faithful loyal to the anti-modernization movement of the late Archbishop Marcel Lefebvre back into the church's fold.

Benedict also lifted the excommunication of three other bishops who broke with the Holy See over the Vatican II reforms to follow Lefebvre's ultraconservative movement.

Williamson's case sparked outrage among Jewish groups and in Israel as well as among Catholic bishops in Germany.

Bowing to criticism by Jewish groups, historians and others, the Vatican demanded Feb. 4 that Williamson "absolutely and unequivocally distance himself" from his Holocaust denial.

Last month, he apologized for the "hurt" that his remarks caused, but he didn't recant what he said. The Vatican called that apology inadequate.

After the furor, Williamson was ordered to leave Argentina, where he had been living, and returned to his native Britain.

State prosecutors in Germany have opened an investigation into whether Williamson broke German laws against Holocaust denial.

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