Staff working on the 2012 Olympic site will only be able to gain access to it via biometric screening.
About 100,000 workers will have to pass through a system that includes palm-print reading and face recognition.
The two-tier biometric system part of a GBP354 million strategy to secure the Olympic Park during construction is one of the largest and most expensive security operations to be undertaken on a British project.
Biometric screens are also being considered for the nine million spectators as they enter.
It was also revealed today that the policeman in charge of the Games, Met Assistant Commissioner Tarique Ghaffur, said that up to 500,000 CCTV cameras would be needed to police the site.
Alan Ritchie, general secretary of Ucatt, the main construction union, said: "We do not foresee a problem, providing the Olympic Delivery Authority guarantees that biometric data will not be passed onto any third parties and will be wiped once the project is complete." The primary concern of the ODA, which has not ruled out sharing biometric data with government agencies, is preventing sabotage of the east London site.
The cost of patrolling the site until 2011 will be more than GBP100 million. It is also estimated that up to 8,000 private security guards will be needed during the Games, at a cost of GBP30 million.
The Met is also awaiting a response from the Home Office about additional resources to cope with the 16,000 athletes and team officials.
Ministers are worried that the security budget could be pushed up by demands unrelated to the Games, having already risen to GBP1.2 billion from the GBP200 million estimated in the 2005 bid..