The Olympics will run from 8 to 24 August
The BBC has called in the police after files holding details of staff going to the Beijing Olympics went missing.
The folders with addresses, passport numbers, pictures, and hotel details of more than 430 staff vanished from Television Centre in west London.
The BBC fears the files have been stolen, possibly for identity theft or an attempt to embarrass the BBC over the number of staff going to the Games.
The corporation says it is sending 437 people from the UK to the Olympics.
The number of people the BBC sends to cover big events has been a subject of controversy in recent years.
But the corporation insists the 437 going this year - 33 more than the Athens games - will provide more than twice as much output as four years ago.
An internal investigation failed to find the files, which are believed to have gone missing two weeks ago.
Roger Mosey, director of BBC Sport, said he did not want to speculate on why the files may have been taken.
He added that a helpline would be set up to deal with any staff concerns.
"We are still in a position where they could have genuinely gone missing, but increasingly our suspicions are that it was deliberate or malicious in some way, and they could well have been stolen," he said.
"Obviously it is potentially upsetting for people that these details have been stolen, however, we believe the risk to individuals is low."
Presenter Sue Barker's details are believed to be in the missing files
The files were held in a secure office in Television Centre, and executives called in the police on Thursday.
The risk of identity theft is believed to be low because the folders contained no financial or medical details.
In a statement, the BBC said: "We can confirm that we are undertaking a full investigation into how two files containing accreditation information for the Beijing Olympics have gone missing from a private office in Television Centre.
"We believe these files may have been stolen, and following our own investigation, we have now involved the police.
"The information in the files includes passport details. However it does not include financial data and internal and external advice that we've taken suggests there is not a high risk of fraud.
"We are in the process of contacting everyone involved and are also reviewing our internal security as a matter of urgency."