Rome  - The Vatican has admitted to "errors" in its handling of a decision to reinstate four ultra-nationalist bishops, including a failure to do internet research that might have raised alarm bells about some of the bishops' beliefs, an Italian newspaper reported Wednesday.

According to Rome-based daily Il Foglio, Pope Benedict XVI conceded the errors in the decision making process to revoke the excommunication of the bishops, one of whom embarrassed the church by denying the scale of the Holocaust.

The German-born pontiff's admission is contained in a letter written to Roman Catholic bishops in which his decision to lift the 1988 excommunication of the four Society of Saint Pius X (SSPX) clerics, is explained, the paper reported.

The Vatican did not comment on the report but said the letter would be published on Thursday with copies available in English, Italian, French, German, Portuguese and Spanish.

According to Il Foglio, in the letter Benedict, referring to remarks by British-born Bishop Richard Williamson denying the extent of the mass murder of Jews by the Nazis, writes that the Vatican needs to pay greater attention to the internet as a source of information.

A television interview in which Williamson said the Nazis did not use gas to kill Jews was broadcast around the time the Vatican announced Benedict's lifting of the excommunications in January.

A row ensued with many Jews, but also Catholics and government officials, including German Chancellor Angela Merkel, demanding an explanation.

The Vatican subsequently said it was not aware of Williamson's views, but critics have pointed out that remarks written by the bishop in which he cast doubt on the historical veracity of the Holocaust have been available on the internet for some time.

According to Il Foglio, Benedict also says the Vatican failed to be "sufficiently clear" in explaining the pontiff's reasons for lifting the ban on the SSPX members.

While not fingering anyone responsible for the mistakes, Benedict in the letter announces that in the future the Vatican body charged with negotiating with the SSPX, the Pontifical Commission Ecclesia Dei, will have to work closely with the church's watchdog on orthodoxy and disciplinary matters, the Congregation for the Doctrine of the Faith.

Besides the row over Williamson, many Catholics were also shocked by statements made by SSPX bishops that, despite the lifting of the excommunication, they have no intention to adhere to modernizing church reforms introduced in the 1960s around which their dispute with the Vatican has centred.

In the letter Benedict reiterates the Vatican' stance that the SSPX clerics remain suspended from holding any official position within the church until they fully subscribe to the so-called Second Vatican Council reforms. (dpa)