London is preparing to welcome some 10,000 athletes, hundreds of thousands of visitors and a worldwide television audience when the Olympic Games formally open Friday.

Organizers have dealt with a series of last-minute problems, including scrambling to ensure enough security personnel after a private contractor reported problems putting together a large enough force.

There was also an dispute between the International Olympic Committee and the families of the 11 Israeli team members who were killed by Palestinian gunmen at the Munich Olympics in 1972.

Secretary of State Hillary Clinton has joined the Israeli government and the victims' families in calling for a moment of silence in their memory Friday night. But the International Olympic Committee President Jacques Rogge has denied the request, saying that the opening ceremonies are not an appropriate venue for the tribute. The victims will be commemorated at a separate event.

The extravagant opening ceremony Friday night will be directed by Danny Boyle, the director of the Oscar-winning movie “Slumdog Millionaire”. The parade of athletes will start with Greece and end with Britain.

Britain's Queen Elizabeth will officially open the games.

On the eve of the opening, British Prime Minister David Cameron said his biggest concern is a “safe and secure” Olympics.

Some 36,000 troops, police and hired contractors will guard the Olympic venues and the streets of London and other British cities. After the private security firm G4S acknowledged earlier this month that it wouldn't be able to secure all of the 10,000 contractors it had agreed to provide, British officials called up additional service members to fill the gap.

The competition in 26 sports runs until August 12.

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