An internal investigation into the behaviour of the Home Office is being conducted after it admitted publishing the details of thousands of people going through the immigration system.
Home Office minister Mark Harper admitted in a written statement that the names, date of birth, and details of the immigration case type and status of 1,598 people had been mistakenly published online by his staff.
The details were part of a spreadsheet about people involved in the family returns process.
They were available to anyone to download for 13 days until someone at the department spotted the mistake on October 28th.
"The Home Office has notified the Information Commissioner's Office and is undertaking an internal investigation," Harper said.
"Measures have been put in place to prevent a recurrence of the error and verify that no similar error has previously taken place.
"Our official assessment is that the risk to those whose personal information was accessible for the period is low. However, I have instructed my officials to take steps to notify those individuals concerned, where it is possible and appropriate to do so."
The personal addresses or financial information of the individuals were not released.
Home Office staff tried to assess whether the data was viewed or accessed outside the Home Office.
Their analysis revealed that there had been less than 30 visits to the webpage, but they could not establish whether visitors opened the spreadsheet or what they viewed on it.
The development comes just days after Theresa May faced calls to resign for a botched deportation in which a Nigerian man was flown to his home country on a chartered flight at a cost of up to £180,000 to the taxpayer.
The plane was sent back to the UK when it emerged May had failed to ask Nigerian authorities for landing authorisation.