The grave of a woman who saved thousands of Jewish children in the Warsaw Ghetto has been desecrated, according to Polish authorities.

The words “Jews out” were sprayed onto the Warsaw gravestone of Irena Sendler, a woman honoured by Holocaust museum Yad Vashem as one of the Righteous Among the Nations.

Police have launched an investigation after the graffiti was discovered in the Warsaw cemetery.

The Catholic social worker rescued 2,500 children from the Nazis during the Holocaust by smuggling them out of the ghetto in bins and suitcases, then placing them in church institutions for the remainder of the war.

Ms Sendler, nominated for the Nobel Peace Prize in 2007, risked her life repeatedly to bring supplies to Jews trapped inside the ghetto. She died, aged 98, in 2008.

The vandalism took place just before the efforts of 50 Righteous Gentiles were celebrated at a special event in Warsaw. The Jewish Foundation for the Righteous said the gathering was one of the largest ever meetings of Holocaust rescuers.

Stanlee Stahl, executive vice president of the Jewish Foundation for the Righteous, said she planned to visit Sendler’s grave following the attack.

She said: “While we are taking this time to honour these Holocaust rescuers, anti s emitism is still prevalent.”

In June several war graves in France were defaced with neon pink swastikas and SS insignia.