The government is offering a £20,000 reward to anyone who finds the missing discs from HM Revenue & Customs containing 25 million child-benefit records, after the initial police search failed to find them.
The search for the missing CDs has been led by a core team of 47 detectives and computer experts from the Metropolitan Police's Specialist and Economic Crime Command.
Now that the main search has finished without finding the CDs, the Metropolitan Police has appealed to all staff at HMRC, the National Audit Office and the Treasury to check at work and "other locations" for the discs. HMRC courier TNT will also ask its staff to help with the search for the CDs.
In addition to the police appeal, HMRC is now offering a reward of "up to £20,000" for information leading to the safe return of the CDs — despite the fact that acting Liberal Democrat leader Vince Cable last week claimed the data on the discs could be worth up to £1.5bn to criminals on the black market.
A statement from the Metropolitan Police said: "The enquiry has been particularly challenging due to how common compact discs are within offices, the number and size of the offices requiring searches and the number of organisations where the package may have travelled through."
The Metropolitan Police maintained there is no evidence the lost data has ended up in the hands of criminals.
Data-protection watchdog the Information Commissioner's Office has also revealed that a number of private and public-sector organisations have come forward and admitted problems with data security following the HMRC breach.