A stolen Ministry of Defence computer had the personal details of almost 60,000 Scots stored on it.
A laptop computer similar to the one that was stolen
The revelation came in a written parliamentary answer to SNP defence spokesman Angus Robertson MP.
The laptop, which was taken from a Royal Navy officer in Birmingham on 9 January, contained information about 600,000 people.
The MoD has set up a freephone help number on 0800 085 3600 for anyone who thinks they may have been affected.
The breakdown given to Mr Robertson disclosed that the details of 59,553 people in Scotland were lost as a result of the theft.
In Wales, the details of 37,546 people were lost, while in Northern Ireland 14,223 people were affected.
The details of 459,778 people from England and 34,667 people from elsewhere were also on the laptop.
Mr Robertson said the scale of the problem was "staggering" and called for a thorough investigation.
Secretary of State for Defence, Des Browne, has said he took the theft of personal data "extremely seriously".
He added: "I am also keenly aware of the risks should the data have fallen into the wrong hands, although I emphasise that there is no evidence that it has done so.
"I am determined that we should identify exactly what went wrong and learn lessons."
Mr Robertson said the MoD's response to his questioning brought home the staggering scale of the data loss.
He added: "The obvious and immediate concern must be the security of individuals, and their families, whose data has stolen, but we also urgently need assurances from the MoD that operational security has not been compromised by this grave breach.
"It is just unfathomable that the MoD could let this happen, and we must now have a top level investigation into data security right across UK Government departments."
The laptop contained personal details of people who had joined the Royal Navy, Royal Marines and Royal Air Force and from people who had expressed an interest in joining.
Entries on the computer included passport details, National Insurance numbers, drivers' licence details, family details, doctors' addresses and NHS numbers, the MoD said.
West Midlands Police began an investigation into the theft of the laptop, and an inquiry into military security was also launched.
The MoD's helpline will be open from 0700 GMT to 1900 GMT, Monday to Friday.
Callers will be asked to provide their name, date of birth and postcode to verify whether they are at risk.