Olympic security officials said Monday that testing is underway for the mammoth task of making the 2012 London Games safe -- trials that include testing body scan machines, communications equipment, response time and extra closed-circuit security cameras.

Testing events have already begun to allow security officials to gauge how well they're able to communicate between venues and Scotland Yard's headquarters, as well as how quickly they feed important data into a government system of dealing with potential crises.

The next big testing cluster of events will start Saturday and end next week. Teams will be on hand to test communications equipment and other systems during such events as sailing and beach volleyball -- events meant to test Olympic venues ahead of the games.

"There is a lot to be done; a lot to be tested," said Commander Bob Broadhurst, head of Scotland Yard's Olympics safety and security operation.

Thousands of extra closed-circuit cameras will be added to Olympic venues -- Britain already has some of the most extensive surveillance powers in the world and has become a leader in what critics call "Big Brother" techniques with its more than 4.3 million CCTV cameras in operation.

Years ago, officials considered using special cameras equipped with eavesdropping microphones.

Ultimately, however, the cameras were considered too intrusive and are no longer part "of our main plan," according to Ian Johnston, director of security and resilience with the Olympic Organizing Committee.

Johnston wouldn't elaborate on other types of security gadgets and equipment being deployed for the games.

Authorities have identified 20 potential risks to the Olympics. The top four include terrorism, serious crime -- specifically ticket fraud -- protests and natural disasters such as floods or heat waves.

British authorities will also be on alert for cybersecurity breaches. The government is investing nearly an extra $1 billion in the country's electronic defenses since it was identified as one of the country's major security risks.

Lulz Security, a hacking collective, has previously claimed hacks on major entertainment companies, FBI partner organizations and the CIA. Another group also claimed it hacked into NATO's computer system.

Security at the Olympics has been a critical issue ever since the 1972 Munich massacre, even more so after the Sept. 11, 2001 terror attacks. A day after London was awarded the games in 2005, suicide bombers attacked London's transport network, killing 52 people.

The British government is planning for the national terror threat to be "severe" during the Olympics, meaning an attempted attack is highly likely.

More than 300 screening points will be installed at Olympic venues. Officials hope the waiting time for spectators will be kept "within single digits," but say the time will largely depend on the venue and the crowds queuing for an event.

Spectators should expect the same type of screening as they encounter at airports -- bags will be put through screening and people will need to walk past a screening point.

Two of the major security contracts have been awarded to G4S, a global security company providing everything from security personnel to monitoring systems, and Rapiscan Systems, headquartered in Torrance, California, which will be providing security equipment and other scanning systems.

About 12,000 police officers will be on duty each day of the July 27-Aug. 12 games, which have a security budget of $770 million.