Seven Israeli Olympians who lost their teammates in the Munich Games massacre nearly 40 years ago returned to the city this week.

In September 1972, 11 members of the Israeli Olympic team died after an attack on their Olympic Village apartments by gunmen from the terrorist group Black September. Some died immediately, others during an unsuccessful rescue attempt which also left a German policeman dead.

The anniversary of the massacre, considered one of the darkest moments in Israeli history, will be marked in London this summer. This week, seven athletes who were on the 1972 team, now in their 60s, were taken back to Munich for a Biography Channel documentary that is being made about what happened.

Swimmer Avraham Melamed said that while it was fantastic to return, "the families of the victims share a completely different reality".

Dan Alon, who competed in fencing, said that he had nothing against the German people. "I have only one thing to blame, it's the terrorists, unfortunately," he said. "We hope that one day, it will be the end of terror around the world."

He said he wanted to appear in the documentary to "tell the world everything that we know".

Speaking in Israel last week, British ambassador Matthew Gould promised this year's Olympians that their security was paramount.

"We are doing everything possible to keep you safe," he said. "Forty years on, the lessons from Munich have not been forgotten."