The Prison Officers' Association hit out, telling BBC news that the Prison Service may have tried to conceal the fact the information had gone. Colin Moses, chairman at the association, said: "We are extremely concerned that not only has this data been lost, but that the Prison Service appear to have tried to conceal this serious breach in security.
"It is a breach that we believe could ultimately cost the taxpayer millions and millions of pounds, because, if the information lost is personal and sensitive, it may well mean staff having to move prisons, move homes and relocate their families."
Nick Lowe, head of Northern Europe at security vendor Check Point, said this situation demonstrated that there needed to be heavy penalties for data breaches. "Perhaps data security will only be taken seriously when there are serious penalties for losses or breaches – as there is with company financial reporting in the US," he said.
"The justice minister, Michael Wills, has promised new powers and penalties against reckless misuse of data. But in the meantime data will still be lost or stolen, because companies think it can't, or won't, happen to them."
The news comes only weeks after the details of 84,000 prisoners were lost by the MoJ. At the time, IT industry analysts told Computerworld UK that the government must make better use of security technology to help prevent data breaches.
Last month, it emerged that the government has lost the details of one in every fifteen people in the country in the last year alone.