The firm said yesterday it had lost a disk containing extensive information on 894,629 emergency calls made to the Scottish Ambulance Service. TNT said it had mislaid the disk four days earlier, but took the intervening period to confirm that the disk was actually lost.
TNT was carrying the data from the Scottish Ambulance Service's dispatch centre in Paisley (Glasgow) to Manchester, where the data was to be analysed to improve the emergency service's IT systems.
A statement by the Scottish Ambulance Service said: "TNT advised us on the 19 June that the package had been mislaid and, following an extensive search, confirmed on the 23 June that the package was missing. The information was a copy of the record of calls to the Ambulance Service in the West of Scotland. If you have phoned 999 for an ambulance since February 2006 then there is a chance that a copy of the information from your 999 call has gone missing."
It said the information included names, phone numbers, the location of each incident and the reason for the call.
Callers affected are mainly in the West of Scotland, but the Paisley centre also deals with calls from outside the area at times of peak demand.
The Ambulance Service said it had followed data protection procedures and that the fault lay with TNT. The information was password-protected and encrypted, it said.
Speaking on BBC Radio, health minister for Scotland Nicola Sturgeon said: "There is absolutely nothing to suggest this information has been stolen. Rather, it has been lost by TNT."