More than 120 USB memory sticks have been lost by the MoD since 2004
The discovery at a Cornish nightclub of a computer memory stick with details of troop movements on it is being probed by the Ministry of Defence (MoD).
The USB stick, outlining training for 70 soldiers from the 3rd Battalion, Yorkshire Regiment, was found on the floor of The Beach in Newquay in May.
Times, locations and travel and accommodation details for the troops were included in files on the device.
The MoD said it would take appropriate action over the "regrettable incident".
A clubber found the memory stick and handed it in to a national newspaper.
The MoD said that it was carrying out a full forensic examination on the stick this week.
It added that it was "undertaking a programme of improvement to safeguard personal data and sensitive information" as recommended in the Burton report.
The report on MoD data losses by Sir Edmund Burton was published in June 2008. He began an investigation after a laptop with the records of 600,000 recruits was stolen from a Royal Navy recruiter's car last January.
It made 51 recommendations about how the MoD should handle data and how data loss incidents should be dealt with.
More than 120 USB memory sticks, some containing secret information, have been lost or stolen from the Ministry of Defence since 2004, it was reported earlier this year.
Some 26 of those disappeared this year - including three which contained information classified as "secret", and 19 which were "restricted".
As well as the MoD data losses, several other stories of government offices losing information have been reported recently.
In August it was revealed that a contractor working for the Home Office lost a memory stick containing personal details of all 84,000 prisoners in England and Wales.