Mr Curtis paid £150 to the homeless man for the device
A BlackBerry sold by a homeless man to a student has been found to contain the personal details of cabinet ministers, top civil servants and police officers.
Journalism student Darryl Curtis said it held hundreds of phone numbers, with data which led him to think it belonged to an ex-Sheffield council chief.
Details of cabinet ministers including Ed Balls and David Miliband were on the BlackBerry, said Mr Curtis, 44.
Police believe it was stolen from a car and that they have traced the owner.
Mr Curtis, who is studying at Sheffield Hallam University, told the Sheffield Star he had bought the device while working on an assignment about homelessness.
"One of the homeless guys knew I was a journalism student and said his friend had a BlackBerry with the numbers for Tony Blair and Buckingham Palace on it," he said.
After paying £150 for the device, Mr Curtis discovered it held the numbers for Mr Balls, the Children's Secretary, and the Foreign Secretary Mr Miliband, along with ex-deputy prime minister John Prescott.
Mr Blair's number was not stored on the device. However, Mr Curtis said he found the National Insurance number, home address and computer passwords of a former chief executive of Sheffield City Council.
Public fears about the security of data held by public bodies have been heightened by a series of high-profile cases involving government departments and hospitals.
A South Yorkshire police spokesman said: "We are satisfied we have traced the owner but an investigation continues into the circumstances of a reported theft.
"There was a theft of a BlackBerry from a car, involving a forced entry, in September 2006. The BlackBerry will remain in police hands until further inquiries are carried out.
"We have made arrangements with the owner to identify the device."