Police were called in to probe the widening laptop scandal, after staff from ACCESS – a city council arms-length organisation – discovered the laptops were missing.
It comes just weeks after red-faced council bosses admitted a computer containing personal data, including bank account details, was stolen.
As reported by the Evening Times last month, Glasgow City Council had to write to almost 38,000 customers warning them of the theft and advising them what action to take.
Bank account details of 10,382 companies and 6069 individuals were included in the information on the laptop. It was one of two stolen from council offices in Cochrane Street between May 28 and May 29.
However, the extent of the security breach did not become apparent until earlier this month.
In a letter to all city councillors, Anne Marie O'Donnell, Executive Director of Corporate Services, wrote: "You will recall that the council suffered the theft of two laptops from City Chambers East last month.
"As part of the investigation it has become apparent that a number of laptops, around 50, have gone missing from the secure area where they were being stored while awaiting disposal.
"As there is no legitimate reason why these laptops might have been removed, staff from ACCESS informed Strathclyde Police who are investigating the matter."
Opposition leader Graeme Hendry today branded the situation "a complete mess".
The SNP councillor, said: "For this to happen so soon after the theft of two laptops, just reflects the failure of management of the security at the City Chambers."
The information on the original stolen laptop, which also includes names and addresses, relates to 17,692 companies and 20,143 individuals.
Those affected include people receiving winter fuel payments, people in receipt of care grants and council suppliers.
The laptop was password-protected but not encrypted.
Council bosses have insisted that the "majority" of the 50 missing laptops were encrypted and secure.
However, the laptops are understood to include details of councillors' expenses, and letters to constituents, as well as policy and research documents.
Strathclyde Police today confirmed an investigation was under way into the incident.
