Pope Benedict has lifted the excommunications of four traditionalist bishops, including a Holocaust denier whose rehabilitation sparked outrage among Jewish groups.

The four bishops were excommunicated 20 years ago after they were consecrated by the late ultraconservative Archbishop Marcel Lefebvre without papal consent — a move the Vatican said at the time was an act of schism.

The Vatican said Saturday that Benedict rehabilitated the four as part of his efforts to bring Lefebvre's Society of St. Pius X back into the Vatican's fold.

But the move came just days after one of the four, British Bishop Richard Williamson, was shown in a Swedish state TV interview saying that historical evidence "is hugely against six million Jews having been deliberately gassed."

Jewish groups denounced the Vatican for having embraced a Holocaust denier and warned that the Pope's decision would have serious implications for Catholic-Jewish relations as well as the pontiff's planned visit to the Holy Land later this year.

"I do not see how business can proceed as usual," said Rabbi David Rosen, Jerusalem-based head of inter-religious affairs at the American Jewish Committee and a key Vatican-Jewish negotiator.

He called for the Pope or a senior adviser to issue a "clear condemnation" of all Holocaust denials and deniers.

Shimon Samuels of the Simon Wiesenthal Centre in Paris said he understood the German-born pontiff's desire for Christian unity but said Benedict could have excluded Williamson. He warned that his rehabilitation will have a "political cost" for the Vatican.

"I'm certain as a man who has known the Nazi regime in his own flesh, he understands you have to be very careful and very selective," Samuels said.

The Vatican spokesman, Rev. Federico Lombardi, said Williamson's views were "absolutely indefensible."

But he denied that rehabilitating Williamson implied that the Vatican shared them.

"They are his personal ideas ... that we certainly don't share but they have nothing to do with the issue of the excommunication and the removal of the excommunication," Lombardi told AP Television News.

Williamson's comments cast a cloud over the Pope's efforts to normalize relations with the Swiss-based Society of St. Pius X, which Lefebvre founded in 1969.

Lefebvre was opposed to the liberalizing reforms of the 1962-65 Second Vatican Council, particularly its ecumenical outreach and its decision to allow mass to be celebrated in local languages instead of Latin.

Despite concerns from liberal Catholics, Benedict has made clear from the start of his pontificate that he wanted to reintegrate the group in the Vatican's fold, meeting within months of his election with the current head of the society, Bishop Bernard Fellay.

In a statement Saturday, Fellay, who is one of the rehabilitated bishops, expressed his gratitude to Benedict and said the decree would help the whole Roman Catholic Church.

"Thanks to this gesture, Catholics attached to tradition throughout the world will no longer be unjustly stigmatized and condemned for having kept the faith of their fathers," Fellay said in a letter to his supporters.