SYDNEY, Australia (AP) -- The Olympic security clamp is closing on Sydney.
Armed police with sniffer dogs and specialist searching equipment began sweeps through the main Olympic precinct Wednesday, searching for bombs and other contraband in preparation for a security "lockdown" of Olympic Park which comes into force on Friday.
In the next two days specialist police and military search teams expect to look under every bleacher, check every nook and examine every cranny of the 760-hectare precinct before declaring it safe and sealing it off.
From then on, access will be permitted only to properly accredited people, undergoing vehicle and bag searches and passing through magnetometers -- airport-style metal detectors.
Similar searches will take place at all Games venues. Security will also be upgraded at other sites around Sydney, including parks and other public sites earmarked for games activities and suburbs adjacent to outdoor games venues.
New South Wales state police commissioner Peter Ryan, who has responsibility for overall Games security, acknowledged Wednesday that the measures were restrictive, but said they were "absolutely essential" for safety at the Olympics.
"We have applied the most sophisticated security approach to these Olympic Games ever, we have done all we can humanly possible to ensure there is a trouble free games," Ryan said.
"But there is no guarantees at all when it comes to terrorism or people who want to create mischief."