Vatican City - Pope Benedict XVI on Wednesday expressed "solidarity" with the Jewish people and asked four recently reinstated bishops to adhere to the Second Vatican Council which prescribes brotherly relations with Jews.

Benedict during his general audience said the reality of the Nazi mass murder of Jews, known as the Holocaust or Shoah cannot be cancelled through any form of denial.

The German-born pontiff remarks come in the wake of mounting pressure on the Vatican to take action after one of the pardoned ultra-traditionalist bishops, Richard Williamson said he did not believe the Holocaust had taken place.

On Monday the Vatican's newspaper described Williamson's assertion as "unacceptable" while on Tuesday the Vatican said the other three bishops had asked Benedict to forgive their colleague while distancing themselves from his remarks.

However, Jewish leaders said the were still not satisfied with the Vatican's response and Israel's Ambassador to the Holy See Mordechai Lewy called on clarity to be made on the issue by the Vatican's "highest levels."

Benedict on Saturday revoked the 1988 excommunication of the four clerics who lead a breakaway ultra-traditionalist Catholic group, the Society of Saint Pius X (SSPX), which broke with Rome over Church reforms introduced in the 1960s through the Second Vatican Council.

In 1988 the group leader, Archbishop Marcel Lefebvre, disobeying orders by Pope John Paul II, consecrated the four men as bishops in a move branded as schismatic by the Vatican and which led to the excommunication of Lefevbre and his four bishops.

The Vatican estimates that the SSPX has around 600,000 members. About 1.1 billion people in the world are described as Roman Catholics. (dpa)