British Bishop Richard Williamson, seen in an Argentine broadcast of a Swedish television interview, stirred controversy when Pope Benedict readmitted him to the Roman Catholic church. Williamson has publicly denied the Holocaust. (Juan Mabromata/AFP/Getty Images)

The Vatican has demanded that a bishop who denied the Holocaust must recant his position before being fully readmitted into the Roman Catholic Church.

The Vatican also said in a statement Wednesday that Pope Benedict XVI didn't know about Bishop Richard Williamson's views when he agreed to lift his excommunication and that of three other ultraconservative bishops last week.

The statement was issued by the Secretariat of State a day after the German Chancellor Angela Merkel urged the Pope to make a clearer rejection of Holocaust denials.

The former cardinal Joseph Ratzinger has also come under fire from the influential German magazine Der Spiegel, which features his image on its most recent cover along with the headline, "A German Pope Disgraces the Catholic Church."

Williamson was shown on Swedish state television days before his rehabilitation was made public saying historical evidence "is hugely against six million Jews having been deliberately gassed" during the Second World War.

He subsequently apologized to the Pope for having stirred controversy, but he did not repudiate his comments, in which he also said only 200,000 to 300,000 Jews were killed during the war and none was gassed.

Williamson and three other bishops were excommunicated in 1988 after they were consecrated by the late ultraconservative Archbishop Marcel Lefebvre without papal consent. In 1969, Lefebvre founded the traditionalist Society of St. Pius X, which opposed to the liberalizing reforms of the Second Vatican Council, including its outreach to Jews.

The Holy See said when it announced the rehabilitation of the bishops on Jan. 24 that removing the excommunication did not mean the Vatican shared Williamson's views. But Jewish groups voiced outrage and demanded that Williamson recant his views.

In the statement Wednesday, the Vatican said that while Williamson's excommunication had been lifted, he still had no canonical function in the church because he was consecrated illegitimately by Lefebvre.

"Bishop Williamson, in order to be admitted to episcopal functions within the church, will have to take his distance, in an absolutely unequivocal and public fashion, from his position on the Shoah, which the Holy Father was not aware of when the excommunication was lifted," the statement said.