The families of 11 Israeli athletes killed by Palestinian attackers at the 1972 Summer Olympics in Munich will not attend a 50-year anniversary ceremony organised by the German authorities, saying they deserve more compensation and a fuller reckoning of the tragedy

The decision underscores a lingering point of friction between the two countries that have built strong ties despite the enduring legacy of the Nazi Holocaust, in which 6 million Jews were murdered during World War II.

Members of the Palestinian group Black September broke into the Olympic Village, killed two athletes from Israel’s national team and took nine more hostage on September 5, 1972. The attackers hoped to force the release of Palestinian prisoners held by Israel as well as two leftwing extremists in West German jails.

All nine hostages and a West German police officer died during a rescue attempt by German forces. Relatives of the athletes accuse Germany of failing to secure the Olympic Village, refusing Israeli help and then botching the rescue operation.

“Fifty years of abuse, lies, humiliation and dismissals by the German Government, and by the Bavarian authorities in particular, are really too much for us,” the group of families wrote in a letter to Bavarian authorities, who are organising the September 5 memorial event.

Ankie Spitzer, the widow of Andre Spitzer, a fencing coach who was among those killed, said the families expected compensation according to international standards governing terror attacks.

“I was 26 when this happened in Munich. I’m 76 now. I don’t need a diamond ring,” she said, adding that the families want “fair and just compensation,” especially for the 14 people who lost parents in the attack and have lived in its shadow for half a century.

“If they don’t want to come close to that with their humiliating offer, then have your ceremonies, but we will not be there,” Spitzer said.

She said the entire Israeli delegation of some 200 people, including Olympic athletes, would stay home.