Polish Catholics last month put up 50 small wooden crosses near the entrance to the camp where more than one million people, mostly Jews, died at the hand of the Nazis.

The crosses surround a controversial 8-metre-high cross - commemorating a Mass which Pope John Paul II attended at Auschwitz in 1979 - which was already on the site.

In a statement Yad Vashem said the new crosses violated an agreement which it reached earlier this year with the US Holocaust Museum in Washington and the Polish government and church authorities.

Under the terms of the pact no religious, ideological or political symbols can be placed on the Auschwitz site.

Auschwitz holds unbearable memories for many Jews

The agreement followed concerns by Jewish groups that Christians were trying to co-opt a site which is one the most powerful symbols of Jewish suffering during the holocaust.

Yad Vashem branded the addition of the new crosses a "provocative act" by "extreme groups."

Jewish groups claimed last week that the crosses were placed on the same site where children were burnt alive in 1944.

The Director of Yad Vashem, Avner Shalev said that the crosses were "very painful for any member of the Jewish people and many others."

Mr Shaley said he hoped government and church officials in Poland would act immediately to remove them.

"Everyone agrees and understands that Auschwitz should be kept in the authentic way that it was left," he said.