The world must "never forget" the 11 Israeli athletes killed at the 1972 Munich Olympics, David Cameron has said at an event to mark the 40th anniversary of the terrorist attack.
Widows of two of the team-mates murdered by Palestinian gunmen were among those attending the commemoration of what the Prime Minister called "one of the darkest days" in Games history.
The UK would remain a "staunch friend" of Israel and work with it to tackle terrorism, including a recent bomb attack that killed six Israeli tourists in Bulgaria, Mr Cameron told them.
"As the world comes together in London to celebrate the Games and the values it represents, it is right that we should stop and remember the 11 Israeli athletes who so tragically lost their lives when those values came under attack in Munich 40 years ago," he said. "It was a truly shocking act of evil. A crime against the Jewish people. A crime against humanity. A crime the world must never forget.
"We remember them today, with you, as fathers, husbands, and athletes, as innocent men, as Olympians and as members of the people of Israel, murdered doing nothing more and nothing less than representing their country in sport."
Deputy Prime Minister Nick Clegg also spoke at the event. He said the Israeli Olympic team showed "immense courage and determination" competing in the games after Munich. Speaking of those who lost their lives, he said: "The world will never know the Olympic glory they could have achieved or the joy their participation would have stirred at home."
The July 7 terrorist atrocity that killed 52 on London's transport system the day after the city was awarded the 2012 Games in 2005 meant British people understand the impact of terrorism, he said. The event, at London's Guildhall, was organised by the National Olympic Committee of Israel, the Jewish Committee for the London Games and the Embassy of Israel.
The two widows, Ankie Spitzer and Ilana Romano, unsuccessfully campaigned for the anniversary to be marked with a minute's silence at the opening ceremony. A minute's silence was held in London's Olympic Village at the signing of the Olympic Truce, the first time it has happened inside an athletes' village.
Mr Cameron was among those who rejected the idea, insisting that the planned memorials were the appropriate way to pay tribute to the victims.
Opposition leader Ed Miliband told the crowd at the event that those who lost their lives in 1972 would never be forgotten. The Labour leader said: "We have seen in London this last week the other side of the Olympics. The joy and celebration it can bring. But we also know for you, the families, each Olympic Games brings terrible memories of grief and despair. Tonight we grieve with you."