A package containing about 200 pension statements has gone missing after being dispatched by a Scottish Government agency, it has emerged.
The Scottish Government is reviewing data handling issues
The printed statements contained names and national insurance numbers but no addresses or bank account details.
A spokesman described it as "a serious matter" and said efforts were continuing to track down the package.
The Liberal Democrats said an "urgent and wide-ranging review of all data management procedures" was needed.
The statements were sent from the Scottish Public Pensions Agency (SPPA) to NHS Greater Glasgow on 26 October.
The package was one of 162 which were sent to 14 separate addresses throughout Scotland by FedEx, the Scottish Government's official courier.
The government spokesman said the other 161 packages, which were dispatched in line with agreed procedures, arrived safely.
A review is being carried out into data handling issues in the Scottish Government.
The spokesman for the SNP Government said: "We consider this to be a serious matter and our enquiries are continuing to ascertain the whereabouts of the unaccounted for package.
"There is no reason to suspect fraud or theft and FedEx are currently working to trace the package.
"If the package remains unaccounted for once enquiries are completed affected individuals will be fully informed."
Scottish Liberal Democrat leader Nicol Stephen said many people would be anxious.
"The Scottish Government needs to have an urgent and wide-ranging review of all data management procedures," he said.
"There are millions of people who have their data stored by the Scottish Government and its agencies.
"The Scottish Government must move quickly to tell us what steps, if any, it has taken to secure our personal data and ensure that it does not make the same mistakes as Customs and Revenue made."
Conservative David Mundell MP, shadow secretary of state for Scotland, said: "Thankfully this incident seems less serious than the catastrophe at Revenue & Customs, but it is imperative that we know all the details of any missing data from any agency and that those individuals affected are informed immediately.
"In light of the disaster at HMRC, we would have hoped that everyone handling personal information would re-assess their procedures to ensure maximum security.
"There seems to have been considerable delay in the data loss being made public - the reason for that delay and confirmation that this is the full extent of the problem should be revealed."
Last week two computer discs holding the personal details of all families in the UK with a child under 16 went missing.
Labour Prime Minister Gordon Brown said he "profoundly regrets" the loss of 25 million child benefit records.